Subjects -> EARTH SCIENCES (Total: 771 journals)
    - EARTH SCIENCES (527 journals)
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EARTH SCIENCES (527 journals)            First | 1 2 3     

Showing 401 - 371 of 371 Journals sorted alphabetically
PFG : Journal of Photogrammetry, Remote Sensing and Geoinformation Science     Hybrid Journal   (Followers: 5)
Photogrammetrie - Fernerkundung - Geoinformation     Full-text available via subscription  
Physical Geography     Hybrid Journal   (Followers: 8)
Physical Science International Journal     Open Access  
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 15)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Metals and Metallography     Hybrid Journal   (Followers: 18)
Physics of Plasmas     Hybrid Journal   (Followers: 11)
Physics of the Earth and Planetary Interiors     Hybrid Journal   (Followers: 34)
Physics of the Solid State     Hybrid Journal   (Followers: 4)
Physics of Wave Phenomena     Hybrid Journal  
Physics World     Full-text available via subscription   (Followers: 18)
Physik in unserer Zeit     Hybrid Journal   (Followers: 9)
Pirineos     Open Access  
Planet     Open Access   (Followers: 4)
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 10)
Plasma Physics Reports     Hybrid Journal   (Followers: 9)
Polar Record     Hybrid Journal   (Followers: 2)
Positioning     Open Access   (Followers: 4)
Pramana     Open Access   (Followers: 13)
Precambrian Research     Hybrid Journal   (Followers: 8)
Preview     Hybrid Journal  
Proceedings of the Geologists' Association     Full-text available via subscription   (Followers: 7)
Proceedings of the Linnean Society of New South Wales     Full-text available via subscription   (Followers: 2)
Proceedings of the Yorkshire Geological Society     Hybrid Journal   (Followers: 2)
Progress in Earth and Planetary Science     Open Access   (Followers: 17)
Pure and Applied Geophysics     Hybrid Journal   (Followers: 13)
Quarterly Journal of Engineering Geology and Hydrogeology     Hybrid Journal   (Followers: 5)
Quaternary     Open Access   (Followers: 2)
Quaternary Australasia     Full-text available via subscription  
Quaternary Geochronology     Hybrid Journal   (Followers: 8)
Quaternary International     Hybrid Journal   (Followers: 15)
Quaternary Research     Full-text available via subscription   (Followers: 21)
Quaternary Science Advances     Open Access   (Followers: 3)
Quaternary Science Reviews     Hybrid Journal   (Followers: 29)
Radiocarbon     Hybrid Journal   (Followers: 13)
Remote Sensing     Open Access   (Followers: 60)
Remote Sensing Applications : Society and Environment     Full-text available via subscription   (Followers: 11)
Remote Sensing in Earth Systems Sciences     Hybrid Journal   (Followers: 5)
Remote Sensing Letters     Hybrid Journal   (Followers: 48)
Remote Sensing Science     Open Access   (Followers: 30)
Rendiconti Lincei     Hybrid Journal  
Reports on Geodesy and Geoinformatics     Open Access   (Followers: 6)
Reports on Mathematical Physics     Full-text available via subscription   (Followers: 2)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
Resource Geology     Hybrid Journal   (Followers: 6)
Resources, Environment and Sustainability     Open Access   (Followers: 4)
Results in Geochemistry     Open Access  
Results in Geophysical Sciences     Open Access   (Followers: 1)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 4)
Reviews of Modern Physics     Full-text available via subscription   (Followers: 32)
Revista Cerrados     Open Access  
Revista de Ciências Exatas Aplicadas e Tecnológicas da Universidade de Passo Fundo : CIATEC-UPF     Open Access  
Revista de Ingenieria Sismica     Open Access  
Revista de Investigaciones en Energía, Medio Ambiente y Tecnología     Open Access  
Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales     Open Access  
Revista de Teledetección     Open Access  
Revista Geológica de Chile     Open Access  
Revue Française de Géotechnique     Hybrid Journal  
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 7)
Rocks & Minerals     Hybrid Journal   (Followers: 3)
Russian Geology and Geophysics     Hybrid Journal   (Followers: 2)
Russian Journal of Mathematical Physics     Full-text available via subscription  
Russian Journal of Pacific Geology     Hybrid Journal  
Russian Physics Journal     Hybrid Journal   (Followers: 1)
Science China Earth Sciences     Hybrid Journal   (Followers: 3)
Science News     Hybrid Journal   (Followers: 10)
Science of Remote Sensing     Open Access   (Followers: 7)
Scientific Annals of Stefan cel Mare University of Suceava. Geography Series     Open Access  
Scientific Journal of Earth Science     Open Access  
Scientific Reports     Open Access   (Followers: 82)
Sedimentary Geology     Hybrid Journal   (Followers: 19)
Sedimentology     Hybrid Journal   (Followers: 14)
Seismic Instruments     Hybrid Journal   (Followers: 1)
Seismological Research Letters     Full-text available via subscription   (Followers: 12)
Soil Dynamics and Earthquake Engineering     Hybrid Journal   (Followers: 14)
Soil Security     Open Access   (Followers: 6)
Solid Earth     Open Access   (Followers: 5)
Solid Earth Discussions     Open Access   (Followers: 1)
Solid Earth Sciences     Open Access   (Followers: 1)
South African Journal of Geomatics     Open Access   (Followers: 2)
Standort - Zeitschrift für angewandte Geographie     Hybrid Journal   (Followers: 3)
Stratigraphy and Geological Correlation     Full-text available via subscription   (Followers: 2)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 1)
Studia Geotechnica et Mechanica     Open Access  
Studia Universitatis Babes-Bolyai, Geologia     Open Access  
Survey Review     Hybrid Journal   (Followers: 6)
Surveys in Geophysics     Hybrid Journal   (Followers: 3)
Swiss Journal of Palaeontology     Hybrid Journal   (Followers: 4)
Tectonics     Full-text available via subscription   (Followers: 15)
Tectonophysics     Hybrid Journal   (Followers: 24)
Tellus A     Open Access   (Followers: 20)
Tellus B     Open Access   (Followers: 20)
Terra Latinoamericana     Open Access  
Terra Nova     Hybrid Journal   (Followers: 5)
The Compass : Earth Science Journal of Sigma Gamma Epsilon     Open Access  
The Holocene     Hybrid Journal   (Followers: 16)
The Leading Edge     Hybrid Journal   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Turkish Journal of Earth Sciences     Open Access  
UD y la Geomática     Open Access  
Unconventional Resources     Open Access  
Underwater Technology: The International Journal of the Society for Underwater     Full-text available via subscription   (Followers: 1)
Universal Journal of Geoscience     Open Access  
Unoesc & Ciência - ACET     Open Access  
Vadose Zone Journal     Open Access   (Followers: 5)
Volcanica     Open Access  
Water     Open Access   (Followers: 11)
Water International     Hybrid Journal   (Followers: 19)
Water Resources     Hybrid Journal   (Followers: 21)
Water Resources Research     Full-text available via subscription   (Followers: 101)
Watershed Ecology and the Environment     Open Access  
Weather, Climate, and Society     Hybrid Journal   (Followers: 14)
Wiley Interdisciplinary Reviews - Climate Change     Hybrid Journal   (Followers: 34)
World Environment     Open Access   (Followers: 1)
Yearbook of the Association of Pacific Coast Geographers     Full-text available via subscription   (Followers: 2)
Yugra State University Bulletin     Open Access   (Followers: 1)
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften     Full-text available via subscription   (Followers: 3)
Zeitschrift für Geomorphologie     Full-text available via subscription   (Followers: 5)
Zitteliana     Open Access   (Followers: 3)
Землеустрій, кадастр і моніторинг земель     Open Access   (Followers: 1)

  First | 1 2 3     

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Physics of Plasmas
Journal Prestige (SJR): 0.576
Citation Impact (citeScore): 1
Number of Followers: 11  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1070-664X - ISSN (Online) 1089-7674
Published by AIP Homepage  [28 journals]
  • Enhanced extreme ultraviolet conversion efficiency of a 2 μm laser-driven
           preformed tin-droplet target using short picosecond pre-pulses

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      Authors: Z. Y. Shi, Y. Yuan, W. P. Wang, Y. Y. Ma, X. Y. Sun, N. Lin, Y. X. Leng
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In this study, an extreme ultraviolet (EUV) conversion efficiency (CE) of 6.9% was obtained in simulation by controlling the delay between a picosecond pre-pulse and a main-pulse with a wavelength of 2 μm; this value is about 7.5% higher than the ns pre-pulse scheme of the EUV emission produced by a 2 μm laser-driven tin-droplet target. In the simulation, the tin droplet expanded into hollow spherical structures after irradiation with a picosecond pre-pulse laser. Notably, compared with a nanosecond pre-pulse, in this case, the density of the tin plasma was lower, and the expansion range was wider for the same delay. Therefore, ps pre-pulse can make the tin plasma reach the optimal state of EUV emission in a shorter delay. In both pre-pulse schemes, the CE value maintains a high value (>5.7%) within a certain delay range (800 ns) between pre-pulse and main-pulse. In this study, the FLASH radiation hydrodynamic code and FLYCHK atomic code were used to investigate the energy conversion and spectra. The results obtained can be potentially useful for EUV lithography under a two-pulse scheme.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:38Z
      DOI: 10.1063/5.0136768
       
  • Investigating boosted decision trees as a guide for inertial confinement
           fusion design

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      Authors: Andrew D. Maris, Shahab F. Khan, Michael M. Pokornik, J. Luc Peterson, Kelli D. Humbird, Steven W. Haan
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Inertial confined fusion experiments at the National Ignition Facility have recently entered a new regime approaching ignition. Improved modeling and exploration of the experimental parameter space were essential to deepening our understanding of the mechanisms that degrade and amplify the neutron yield. The growing prevalence of machine learning in fusion studies opens a new avenue for investigation. In this paper, we have applied the Gradient-Boosted Decision Tree machine-learning architecture to further explore the parameter space and find correlations with the neutron yield, a key performance indicator. We find reasonable agreement between the measured and predicted yield, with a mean absolute percentage error on a randomly assigned test set of 35.5%. This model finds the characteristics of the laser pulse to be the most influential in prediction, as well as the hohlraum laser entrance hole diameter and an enhanced capsule fabrication technique. We used the trained model to scan over the design space of experiments from three different campaigns to evaluate the potential of this technique to provide design changes that could improve the resulting neutron yield. While these data-driven model cannot predict ignition without examples of ignited shots in the training set, it can be used to indicate that an unseen shot design will at least be in the upper range of previously observed neutron yields.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:36Z
      DOI: 10.1063/5.0111627
       
  • Reactive molecular dynamics simulations on interaction mechanisms of cold
           atmospheric plasmas and peptides

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      Authors: Jin-Sen Guo, Shu-Qi Tian, Yuan-Tao Zhang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Plasma medicine is a rapidly growing multidisciplinary field, which mainly focuses on the application of Cold Atmospheric Plasma (CAP) in bioengineering. Several experiments have suggested that amino acids in proteins are excellent targets for plasma-derived chemical species. To gain a deep insight into the oxidative modification of proteins induced by CAP, a ReaxFF-based reactive Molecular Dynamics simulations are performed to investigate the reaction mechanism of Reactive Oxygen Species produced in CAP and the model peptides. The simulation results show that sulfur-containing amino acids with high reactivity could be oxidized to sulfuric acid moiety through sulfonation, and only H-abstraction reaction can take place for aromatic amino acids. The oxidation of five-membered ring amino acids could be observed by yielding the ring-open products in the simulations. Additionally, the dehydrogenation and hydroxylation of carbon-chain amino acids were also found from the simulations, with the formation of the hydroxyl group. The polar amino acids with the electron-rich structure were oxidized to a variety of products, such as di-hydroxylated lysine and hydroxylated asparagine. This study provides a crucial step to understand the processes of oxidative modifications and inactivation of proteins induced by CAP, showing a deep insight on the mechanism of plasma medicine.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:33Z
      DOI: 10.1063/5.0139634
       
  • Ion dynamics in strongly coupled ultracold neutral plasmas at the early
           stage

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      Authors: Feng Fang, Wenchang Zhou, Changjie Luo, Yufan Li, Rui Cheng, Xinwen Ma, Jie Yang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We measured the velocity distribution of ions in the ultracold neutral plasma (UNP) during its early evolution by the technique of velocity map imaging. The ion temperature during the phase of ion equilibrium was obtained experimentally through this method. The Coulomb coupling parameter of ions in the UNP after disorder-induced heating was also determined to be 2.1, which agreed well with the prediction from a charged particle tracing simulation. In addition, the ion expansion during the ion equilibration phase was observed. Notably, the experimentally observed expansion speed is larger than the value obtained from the self-similar expansion model, indicating the involvement of additional mechanisms, besides the electron thermal pressure, in driving the ion expansion. We have also discussed the contributions of ion–ion correlations and charge imbalance to the plasma expansion.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:32Z
      DOI: 10.1063/5.0136369
       
  • The contribution of femtosecond laser filaments to positive and negative
           breakdown discharge in a long air gap

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      Authors: Zhehao Pei, Weijiang Chen, Xing Fan, Jianwei Gu, Shengxin Huang, Xiaosong Liu, Zhong Fu, Bin Du, Tiejun Wang, Rui Zhang, Qiaogen Zhang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Discharges of different polarities develop in different modes, resulting in different guiding effects by femtosecond laser filaments. Knowledge of the contribution of laser filaments to positive and negative discharges is the basis of the laser-guided long-air-gap discharge technique. This study presents a direct comparison of the inception, propagation, and breakdown characteristics of discharges of both polarities. Long-air-gap discharge experiments under the switching impulses of both polarities are carried out under the same experimental conditions. Discharge modes and phases are also considered. The statistical results show that positive discharge inception voltages are transformed from a Weibull distribution into an exponential distribution under the influence of laser filaments, but there is little effect on the negative discharge inception voltage. The guidance probability of a positive discharge reaches 15% at most during the dark period stage, leading to little effect on the breakdown discharge probability. However, for negative discharges, the guidance probability can exceed 95%. An investigation of the filament contributions to both polarity discharges shows that the different migration directions of photoelectrons lead to a difference in the effects of laser filaments on inception voltages, and the difference in the connection of the two discharge passages leads to a difference in the guidance probability. Through the results of a simulation model, it is speculated that the connection condition for positive discharges is that the positive leader overlaps with the laser filaments, and, for negative discharges, the rod electrode is connected to the laser filaments through bi-directional discharge propagation.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:31Z
      DOI: 10.1063/5.0138646
       
  • Characteristics of atmospheric pressure Ar-plasma around a spherical
           particle: Numerical study

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      Authors: I. V. Krivtsun, A. I. Momot, D. V. Antoniv, Binhao Qin
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The characteristics of atmospheric pressure Ar-plasma such as the spatial distributions of number densities, fluxes, and temperatures of electrons and heavy plasma particles, as well as the spatial distribution of electric potential around an individual spherical particle, were studied numerically on the basis of the hydrodynamic (diffusion) equations for plasma components. The governing equations were formulated for plasma that is not in thermal and ionization equilibrium. The boundary conditions near the particle were set on the edge of the space charge layer (sheath) adjacent to the particle surface. The nonlinear problem was solved taking into account the temperature dependencies of transport and kinetic coefficients. The heat flux introduced by the plasma into the particle was calculated and compared with the results of the simple heat conduction model. The range [math] m of particle radius and the range 6–18 kK of unperturbed plasma temperature were considered.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:30Z
      DOI: 10.1063/5.0141015
       
  • Excitation of surface waves in 3D ion beam neutralization

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      Authors: Nakul Nuwal, Deborah A. Levin, Igor D. Kaganovich
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Neutralization of beams with 2D and 3D geometries by the electrons emitted from an external source is studied using particle-in-cell simulations. Our work reveals that the high-energy electrons excite Trivelpiece–Gould (TG) surface waves in the beams with 3D axisymmetric geometries. These high-energy electrons are generated because of a large amplitude electrostatic solitary wave (ESW) that forms near the electron source and has an electric potential amplitude more than three times the electron thermal energy. We also find that surface wave excitation only happens when the beam radius is large enough at the ion source to attract enough electrons that could form the large amplitude ESW. A comparison of the 3D TG surface wave dispersion relation with an expression for 2D surface waves reveals that they become excited in 3D axisymmetric but not in 2D planar beam because of a higher phase speed requirement in the latter case.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:28Z
      DOI: 10.1063/5.0131447
       
  • Enhancement of guided electromagnetic wave by pre-plasma formation in
           laser–plasma interaction

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      Authors: Y. Z. Li, M. J. Wu, D. Y. Li, T. Yang, H. Cheng, Y. D. Xia, Y. Yan, Y. X. Geng, Y. Y. Zhao, C. Lin, X. Q. Yan
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Previous studies have shown that adding a section of critical density plasma on the front surface of solid target can effectively improve the laser energy absorption efficiency. Here, we have investigated laser–plasma interactions with different scale lengths of plasma in front of the target created by a pre-ablation laser pulse. A variety of experimental diagnostics employed together with particle-in-cell simulations give us deep insight into these processes. We found that the laser-induced electromagnetic pulse (EMP) intensity inside the target chamber and the target normal sheath acceleration sheath field accelerated protons were promoted using pre-plasma. The transient current due to hot electron emissions is considered to be one of the main radiation sources of EMP emissions within our measurement bandwidth. In our experiment, this current was guided to a grounded conductive wire attached to the rear surface of the target and measured by proton dynamic imaging technique. The discharging currents together with the guided fields were enhanced more than twice. The reflection spectra of experiments and simulations are compared, which reveal that the energy absorption efficiency was increased with proper plasma scale length, resulting in all the measured signals promoted.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:25Z
      DOI: 10.1063/5.0135323
       
  • Numerical study on mechanisms of period-doubling bifurcation in pulsed
           dielectric barrier discharges at atmospheric pressure

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      Authors: Shu-Han Gao, Xu-Cheng Wang, Yuan-Tao Zhang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In this paper, the mechanisms of the period-doubling bifurcation in pulsed Dielectric Barrier Discharges (DBDs) are numerically investigated at atmospheric pressure. Under the given discharge conditions, the pulsed DBDs could maintain a normal period-1 (P1) state at relatively larger repetition frequencies over 40 kHz, by decreasing the repetition frequency, namely, keeping the duration of the power-on phase unchanged but increasing the duration of the power-off phase, the simulation shows that the discharge bifurcates into a period-2 (P2) state after a transient period of instability. Although the charged particles can diffuse to the surface of dielectric plates more fully at a lower repetition frequency, the large quantities of ions in the sheath region produced by the relatively larger discharge current that have not yet dissipated completely before the next discharge event are proposed to play an important role in the discharge bifurcation process, and the spatial profiles of the charged particle density, electric field, and space charge density in the sheath region before the discharge ignition are examined deeply to further explore the corresponding underpinning physics. The large density of residual ions in the sheath region with the enhanced electric field can weaken the subsequent discharge event and induce the discharge to enter the period-doubling state. Moreover, the computational data indicate that the discharge evolves into the period-4 (P4) and period-8 (P8) state when the repetition frequency approaches 30 and 26 kHz at the given discharge conditions. The simulation data can effectively facilitate the understanding of the temporal nonlinear behaviors in pulsed DBDs and propose ways to further control the plasma stability in applications.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:22Z
      DOI: 10.1063/5.0125956
       
  • Numerical simulation of the hysteresis of the transition from the
           stationary to oscillatory regime in the low-pressure DC glow discharge

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      Authors: Zijia Chu, Jingfeng Yao, Chengxun Yuan, Zhongxiang Zhou, Anatoly Kudryavtsev, Ying Wang, Xiaoou Wang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      As a typical highly nonlinear medium, laboratory plasmas can exhibit abundant nonlinear phenomena. It is well known that the presence of negative differential conductivity can cause the system to exhibit temporal chaotic oscillations when a DC glow discharge is operated in the subnormal glow discharge regime. In addition, for a nonlinear system, the hysteresis often occurs due to the coexistence of multiple attractors. In this work, a two-dimensional plasma fluid model based on the drift-diffusion approximation is developed to study the hysteresis phenomenon of the nonlinear dynamical behaviors of the low-pressure DC glow discharge. The results demonstrate that the initial discharge conditions selected in calculations will influence the nonlinear dynamical behaviors significantly that the system exhibits. Hysteresis can be observed from the voltage waveform when the applied voltage is altered to allow the system to work between the stationary discharge regime and the oscillatory discharge regime. In the hysteresis region, the system exhibits bi-stable characteristics. Near the critical point, the dynamical behaviors of the system will jump from the stationary state to the oscillatory state under small perturbations and the reverse adjustment of control parameters will not immediately restore the original stationary state, which is a typical characteristic of the subcritical Hopf bifurcation.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:21Z
      DOI: 10.1063/5.0142616
       
  • On characterization of shock propagation and radiative preheating in x-ray
           driven high-density carbon foils

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      Authors: Gaurav Mishra, Karabi Ghosh
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Recently, much effort has been dedicated to the high-density carbon ablator coated fuel capsule in indirect drive inertial confinement fusion experiments due to its higher density compared to other ablators. By using detailed radiation hydrodynamic simulations over a broad range of drive and target parameters, a thorough analysis is performed on shock speed, shock breakout, and maximum preheating temperature in pure and tungsten doped high density carbon foils. The ablators are irradiated by a non-equilibrium x-ray temperature drive consisting of the usual Planckian plus an additionally imposed Gaussian distribution lying in the high frequency M-band region of the incident spectrum. All variables have shown a complex interdependence on strength of the drive, its spectral distribution, and the thickness of the target. Maximum preheating temperature, an important parameter in designing experiments, reduces up to 34% for thicker high-density carbon (HDC) foils, whereas a mere 0.44% doping of tungsten in pure HDC is able to reduce preheating up to 17% for extreme drive conditions. The results are explained on the basis of variation of average albedo/wall loss behavior in foils, an outcome of the interplay between total extinction coefficient and spectral intensity variation with photon energy. For a better understanding and comparison among different types of ablators, multi-parameter scaling relations are proposed for above-mentioned variables, which govern the dynamics of shock propagation and preheating phenomena in HDC based foils.
      Citation: Physics of Plasmas
      PubDate: 2023-04-14T02:02:15Z
      DOI: 10.1063/5.0141980
       
  • Transition of a 2D crystal to a non-equilibrium two-phase coexistence
           state

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      Authors: Swarnima Singh, P. Bandyopadhyay, Krishan Kumar, M. G. Hariprasad, S. Arumugam, A. Sen
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In this paper, we present experimental observation of the transition of a 2D dust crystal to a non-equilibrium solid–liquid phase coexistence state. The experiments have been carried out in an L-shaped dusty plasma experimental device in a DC glow discharge argon plasma environment. Initially, a monolayer crystalline structure is formed, which is later transformed to a two-phase coexistence state using the background neutral pressure as a control parameter. Self-excited horizontal oscillations are found in the center of the monolayer prior to the appearance of the coexistence state. It is observed that a molten center coexists with a solid periphery. Various structural, thermodynamic, and dynamical quantities are used to characterize the phase state. The surface tension at the solid–liquid circular interface is also determined. A detailed parametric study is made to delineate the existence region of such a state. It is found that melting caused at the core is due to the onset of a localized Schweigert instability in the presence of a few stray particles beneath the top layer in that region.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:13:04Z
      DOI: 10.1063/5.0139228
       
  • Toward developing a comprehensive algorithm for solving kinetic plasma
           dispersion relations for parallel propagation with a kappa distribution

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      Authors: Wei Bai, Huasheng Xie
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In general, it is challenging to numerically solve all the roots of plasma wave dispersion relations. The velocity distributions of multi-component particles in an anisotropic high-energy plasma can be better described by a drift loss-cone bi-Kappa distribution or a mixed drift loss-cone distribution containing bi-Kappa and bi-Maxwellian plasma in space and laboratories. In this work, we have developed a code with a new numerical algorithm to solve all roots of the kinetic dispersion relation for parallel propagation in hot magnetized plasmas with drift loss-cone bi-Kappa distribution. Solving all roots of the rational expansions of the kinetic dispersion relation is equivalent to a matrix eigenvalue problem of a linear system. We have performed detailed numerical solutions for three kinds of plasmas: bi-Maxwellian, bi-Kappa, and cold plasmas. We have also proposed a unified numerical method to solve the mixed dispersion relation based on the bi-Kappa and bi-Maxwellian distributions. The numerical results and benchmark studies demonstrate that the new algorithm is in agreement with the data from previous studies. This is a crucial step toward revealing a full picture of kinetic plasma waves and instabilities.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:13:03Z
      DOI: 10.1063/5.0140875
       
  • Influence of the axial oscillations on the electron cyclotron drift
           instability and electron transport in Hall thrusters

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      Authors: Lulu Quan, Yong Cao, Yang Li, Hongtao Liu, Bin Tian
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      A 2D-3V finite-element particle-in-cell model, which is applied to simulate the radial-azimuthal plane near the exit of Hall thrusters, has been presented to investigate the influence of axial oscillation on electron cyclotron drift instability (ECDI) and anomalous cross field electron transports. The simplified theoretical analysis about the ECDI and the anomalous electron transport has been introduced. The uniform and harmonic axial electric fields, which are based on the typical axial oscillations in Hall thrusters, have been considered in the simulations. It is concluded that different constant axial electric fields can influence the properties of instability but cannot significantly change the cross field electron mobility. However, the axial oscillation plays a significant role in the instability, and the electron transports provided that appropriate amplitudes and frequencies are achieved. The equilibrium of the instability is destroyed and reformed with the axial oscillation. The cross field electron transports are enhanced in the range of low amplitudes and frequencies and are suppressed when they are in a high value. In addition, it is observed that the variation of the electron mobility and electron–ion friction force show high consistency with the trend of electron temperature. It is further confirmed that the increase in electron temperature takes responsibility for the enhanced cross field electron transport due to the axial oscillation.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:12:04Z
      DOI: 10.1063/5.0134644
       
  • Design of a plasma-based intelligent reflecting surface

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      Authors: M. Magarotto, L. Schenato, P. De Carlo, M. Santagiustina, A. Galtarossa, A.-D. Capobianco
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Plasma-based intelligent reflecting surfaces (IRSs) have been recently proposed to reconfigure the radiation environment between transmitting and receiving antennas. Plasma-based IRSs rely on elements whose electromagnetic response is electronically controlled by varying the plasma density. Here, for the first time, the numerical design of an IRS is based on plasma discharges at the state-of-the-art. First, a cylindrical discharge has been realized and tested to identify realistic plasma parameters and geometries. Second, the design of a plasma-based IRS is proposed, accounting for practical constraints, such as the presence of the glass vessels needed to confine the plasma, the metal electrodes used to sustain the discharge, and the non-uniformity of the plasma parameters (e.g., density). Remarkably, at a central frequency of 10 GHz, a fractional bandwidth larger than 10% is feasible.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:12:03Z
      DOI: 10.1063/5.0142926
       
  • Laboratory study of the failed torus mechanism in arched, line-tied,
           magnetic flux ropes

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      Authors: Andrew Alt, Hantao Ji, Jongsoo Yoo, Sayak Bose, Aaron Goodman, Masaaki Yamada
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Coronal mass ejections (CMEs) are some of the most energetic and violent events in our solar system. The prediction and understanding of CMEs are of particular importance due to the impact that they can have on Earth-based satellite systems and, in extreme cases, ground-based electronics. CMEs often occur when long-lived magnetic flux ropes (MFRs) anchored to the solar surface destabilize and erupt away from the Sun. One potential cause for these eruptions is an ideal magnetohydrodynamic (MHD) instability, such as the kink or torus instability. Previous experiments on the magnetic reconnection experiment revealed a class of MFRs that were torus-unstable but kink-stable, which failed to erupt. These “failed-tori” went through a process similar to Taylor relaxation, where the toroidal current was redistributed before the eruption ultimately failed. We have investigated this behavior through additional diagnostics that measure the current distribution at the foot points and the energy distribution before and after an event. These measurements indicate that ideal MHD effects are sufficient to explain the energy distribution changes during failed torus events. This excludes Taylor relaxation as a possible mechanism of current redistribution during an event. A new model that only requires non-ideal effects in a thin layer above the electrodes is presented to explain the observed phenomena. This work broadens our understanding of the stability of MFRs and the mechanism behind the failed torus through the improved prediction of the torus instability and through new diagnostics to measure the energy inventory and current profile at the foot points.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:11:24Z
      DOI: 10.1063/5.0137457
       
  • Enabling technology for global 3D + 3V hybrid-Vlasov simulations of
           near-Earth space

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      Authors: Urs Ganse, Tuomas Koskela, Markus Battarbee, Yann Pfau-Kempf, Konstantinos Papadakis, Markku Alho, Maarja Bussov, Giulia Cozzani, Maxime Dubart, Harriet George, Evgeny Gordeev, Maxime Grandin, Konstantinos Horaites, Jonas Suni, Vertti Tarvus, Fasil Tesema Kebede, Lucile Turc, Hongyang Zhou, Minna Palmroth
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We present methods and algorithms that allow the Vlasiator code to run global, three-dimensional hybrid-Vlasov simulations of Earth's entire magnetosphere. The key ingredients that make Vlasov simulations at magnetospheric scales possible are the sparse velocity space implementation and spatial adaptive mesh refinement. We outline the algorithmic improvement of the semi-Lagrangian solver for six-dimensional phase space quantities, discuss the coupling of Vlasov and Maxwell equations' solvers in a refined mesh, and provide performance figures from simulation test runs that demonstrate the scalability of this simulation system to full magnetospheric runs.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:11:23Z
      DOI: 10.1063/5.0134387
       
  • Impact of the radial density profile on the Z-pinch stability at a
           microsecond rise time of the driving current

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      Authors: R. K. Cherdizov, R. B. Baksht, V. A. Kokshenev, A. G. Rousskikh, A. V. Shishlov, D. L. Shmelev, A. S. Zhigalin, V. I. Oreshkin
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      This paper considers the instabilities of imploding aluminum metal-puff Z-pinches with an outer plasma shell. An experiment was performed on the GIT-12 generator (3.2–3.6 MA, ∼1 μs implosion times, and ∼15 cm initial Z-pinch radius). It was shown that the density profile of the Z-pinch material had the dominant effect on the growth and suppression of instabilities. Two Z-pinch load configurations were used. The first configuration provided a tailored density profile (TDP) [A. L. Velikovich et al., Phys. Rev. Lett. 77, 853 (1996)], which ensured the suppression of the magneto-Rayleigh–Taylor (MRT) instability in the Z-pinch. For the second configuration, the density profile was changed in such a way that a density notch from 10 to 0.5 μg/cm3 occurred at a radius of about 3 cm from the Z-pinch axis. The notch in the density profile and the nonmonotonic increase in density resulted in a completely unstable compression of the Z-pinch. This gave rise to large-scale instabilities, which were detected by optical diagnostics. The instabilities grew and were not suppressed even in the stagnation phase, despite a sharp increase in the density of the Z-pinch material near the axis. The results were interpreted using the model proposed by Curzon et al. [Proc. R. Soc. London A 257, 386 (1960)]. The total instability amplitude is the sum of the amplitudes of MRT and magneto-hydrodynamic (MHD) instabilities. The growth of the total instability in the density notch region is due to the development of MRT instability. Thus, if the density profile has a notch, the Z-pinch compression in the stagnation phase occurs under strong perturbations at the magnetic field/plasma interface. This results in a dramatic growth of MHD instabilities. Hence, a stable implosion of a Z-pinch with TDP is possible only if the density increases monotonically toward the axis.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:04:16Z
      DOI: 10.1063/5.0132064
       
  • Alfvén mode induced particle loss in LHD

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      Authors: Roscoe White, Kunihiro Ogawa
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Losses of beam ions due to Alfvén modes are simulated for discharges in the Large Helical Device at Toki, Japan, using a guiding center code. High frequency beam particle resonances are found for the equilibria for passing particles, providing locations for the destablization of Alfvén modes observed in the device. Losses due to even small modes due to these resonances are significant.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:04:15Z
      DOI: 10.1063/5.0145559
       
  • Transition from ITG to MTM linear instabilities near pedestals of high
           density plasmas

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      Authors: J. McClenaghan, T. Slendebroek, G. M. Staebler, S. P. Smith, O. M. Meneghini, B. A. Grierson, K. E. Thome, G. Avdeeva, L. L. Lao, J. Candy, W. Guttenfelder
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Investigation of linear gyrokinetic ion-scale modes ([math]) finds that a transition from ion temperature gradient to microtearing mode (MTM) dominance occurs as the density is increased near the pedestal region of a parameterized DIII-D sized tokamak. H-modes profile densities, temperatures, and equilibria are parameterized utilizing the OMFIT PRO_create module. With these profiles, linear gyrokinetic ion-scale instabilities are predicted with CGYRO. This transition (nMTM) has a weak dependence on radial location in the region near the top of the pedestal ([math]), which allows simulating single radii to examine the approximate scaling of nMTM with global parameters. The critical nMTM is found to scale with plasma current. Additionally, increasing the minor radius by decreasing the aspect ratio and increasing the major radius are found to reduce nMTM. However, any relationship between nMTM and density limit physics remains unclear as nMTM increases relative to the Greenwald density with larger minor radius and with larger magnetic field, suggesting that the transport due to MTM may be less important for a reactor. Additionally, nMTM is sensitive to the pedestal temperature, the local electron and ion gradients, the ratio of ion to electron temperature [math], and the current profile. MTMs are predicted to be the dominant instability in the core at similar Greenwald fractions for DIII-D, NSTX, and NSTX-U H-mode experiments, supporting the results of the parameterized study. Additionally, MTMs continue to be the dominant linear instability in a DIII-D L-mode after an H–L transition as the plasma approaches a density limit disruption despite the large change in plasma profiles.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:04:14Z
      DOI: 10.1063/5.0141179
       
  • Direct stellarator coil optimization for nested magnetic surfaces with
           precise quasi-symmetry

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      Authors: Andrew Giuliani, Florian Wechsung, Antoine Cerfon, Matt Landreman, Georg Stadler
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We present a robust optimization algorithm for the design of electromagnetic coils that generate vacuum magnetic fields with nested flux surfaces and precise quasi-symmetry. The method is based on a bilevel optimization problem, where the outer coil optimization is constrained by a set of inner least squares optimization problems whose solutions describe magnetic surfaces. The outer optimization objective targets coils that generate a field with nested magnetic surfaces and good quasi-symmetry. The inner optimization problems identify magnetic surfaces when they exist, and approximate surfaces in the presence of magnetic islands or chaos. We show that this formulation can be used to heal islands and chaos, thus producing coils that result in magnetic fields with precise quasi-symmetry. We show that the method can be initialized with coils from the traditional two-stage coil design process, as well as coils from a near-axis expansion optimization. We present a numerical example where island chains are healed and quasi-symmetry is optimized up to surfaces with aspect ratio 6. Another numerical example illustrates that the aspect ratio of nested flux surfaces with optimized quasi-symmetry can be decreased from 6 to approximately 4. The last example shows that our approach is robust and a cold-start using coils from a near-axis expansion optimization.
      Citation: Physics of Plasmas
      PubDate: 2023-04-13T04:04:13Z
      DOI: 10.1063/5.0129716
       
  • Ion-driven destabilization of a toroidal electron plasma—A 3D3V PIC
           simulation

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      Authors: S. Khamaru, R. Ganesh, M. Sengupta
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Ion-driven destabilization of a toroidal electron plasma in a small aspect ratio axisymmetric toroidal device is reported for [math] ions of different initial density values using a high fidelity 3D3V PIC solver. Stability of a recently discovered quiescent quasi-steady state (QQS) of a toroidal electron plasma obtained from “seed” solution as a result of entropy extremization at zero inertia is addressed in the presence of a small ion population. An initial value (f0) of the ion fraction (f = [math]) and the corresponding secondary electrons are “preloaded” into the system after the electron plasma attains a QQS state. This procedure is regarded as a proxy to the conventional production of ions in the experimental devices via impact ionization. The resulting electron plasma exhibits destabilized “center of charge motion” (m = 1) along with higher order harmonics with dominant power in the second harmonic. Gradual loss of ions (and also electrons) is observed resulting in time varying f values. Beyond a certain value of f0 ([math] 0.005), growth in wall probe current is observed, which saturates at later simulation time due to the loss of particles. Trajectories of ion particles indicate ion trapping in the potential well, which is qualitatively similar to the ion resonance instability in pure electron plasmas.
      Citation: Physics of Plasmas
      PubDate: 2023-04-11T04:48:55Z
      DOI: 10.1063/5.0112962
       
  • Electron impact ionization cross sections of highly charged open L-shell
           tungsten ions

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      Authors: Zhencen He, Ben Niu, Gang Xiong, Liangyu Huang, Jialin Liu, Liang Liu, Zhimin Hu, Chongyang Chen, Baoren Wei, Yaming Zou, Ke Yao
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      L-shell electron-impact ionization (EII) cross sections for highly charged tungsten ions were measured at incident electron energies of 29.10 and 38.92 keV using the Shanghai-EBIT. Resolved x-rays from radiative recombination (RR) processes were recorded with a high-purity Ge detector in a static electron energy scanning mode. Absolute EII cross sections were obtained by normalizing to the theoretical RR cross sections. The experimental results were compared with the calculated results using the relativistic distorted-wave method implemented in the flexible atomic code and the relativistic Lotz semi-empirical equation. The measurements showed general agreement with the calculated results by two theoretical methods for Li- to N-like W ions. The experimental uncertainties are not sufficiently small to discern the two theoretical results. Furthermore, the influence of Breit interaction on the EII cross sections of open L-shell tungsten ions was studied, and the effect is small but non-negligible. The measured EII cross sections of open L-shell tungsten ions would contribute to fusion plasma studies.
      Citation: Physics of Plasmas
      PubDate: 2023-04-11T04:48:54Z
      DOI: 10.1063/5.0142632
       
  • Investigation of stochastic heating and its influence on plasma radial
           uniformity in biased inductively coupled Ar discharges by hybrid
           simulation

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      Authors: Jia-Wei Huang, Ming-Liang Zhao, Yu-Ru Zhang, Fei Gao, You-Nian Wang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      A bias power is usually applied in inductively coupled plasmas (ICP) to realize the separate control of the plasma density and the ion energy. In this research, a two-dimensional fluid/electron Monte Carlo hybrid model is developed to self-consistently investigate the bias effect on the stochastic heating and on the radial homogeneity in a biased argon ICP operated at low pressure (3 mTorr). The results show that the temporal evolution of the stochastic heating exhibits a plateau and a peak when the sheath collapses at high bias voltages, due to the limited sheath heating and the electron inertia. In addition, the plasma density in the diffusion chamber increases with bias voltage and bias frequency, because of the more pronounced stochastic heating both at the substrate and at the grounded wall. In the main discharge chamber, the plasma density decreases with bias voltage, due to the compression of the bulk plasma region, and this trend becomes less obvious at high bias frequency, because of the enhanced power absorption caused by the stochastic heating. Therefore, it is concluded that by tuning the bias voltage and bias frequency, the plasma radial uniformity could be modulated efficiently, which is very important for improving plasma processing.
      Citation: Physics of Plasmas
      PubDate: 2023-04-10T04:28:46Z
      DOI: 10.1063/5.0142345
       
  • Effect of overlapping laser beams and density scale length in laser-plasma
           instability experiments on OMEGA EP

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      Authors: M. J. Rosenberg, A. A. Solodov, J. F. Myatt, S. Hironaka, J. Sivajeyan, R. K. Follett, T. Filkins, A. V. Maximov, C. Ren, S. Cao, P. Michel, M. S. Wei, J. P. Palastro, R. H. H. Scott, K. Glize, S. P. Regan
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Experiments have been conducted on the OMEGA EP laser facility to study the effect of density scale length and overlapping beam geometry on laser-plasma instabilities near and below the quarter-critical density. Experiments were conducted in both planar geometry (density scale length [math] [math] 190 to 300 [math]m) and spherical geometry ([math] [math] 150 [math]m) with up to four overlapping beams and were designed to have overlapped intensities and density scale lengths comparable to OMEGA spherical experiments, but with many fewer beams. In comparison with previous experiments on OMEGA and National Ignition Facility, it is confirmed that shorter density scale lengths favor the two-plasmon decay (TPD) instability, while longer density scale lengths favor stimulated Raman scattering (SRS). In addition, for experiments at the same scale length and overlapped laser intensity, higher single-beam intensities favor SRS, while a larger number of overlapping beams favor TPD.
      Citation: Physics of Plasmas
      PubDate: 2023-04-10T04:28:43Z
      DOI: 10.1063/5.0135603
       
  • Super-Fermi acceleration in multiscale MHD reconnection

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      Authors: Stephen Majeski, Hantao Ji
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We investigate the Fermi acceleration of charged particles in 2D MHD anti-parallel plasmoid reconnection, finding a drastic enhancement in energization rate [math] over a standard Fermi model of [math]. The shrinking particle orbit width around a magnetic island due to [math] drift produces a [math] power law with [math]. The increase in the maximum possible energy gain of a particle within a plasmoid due to the enhanced efficiency increases with the plasmoid size and is by multiple factors of 10 in the case of solar flares and much more for larger plasmas. Including the effects of the non-constant [math] drift rates leads to further variation in power law indices from [math] to [math], decreasing with plasmoid size at the time of injection. The implications for energetic particle spectra are discussed alongside applications to 3D plasmoid reconnection and the effects of a guide field.
      Citation: Physics of Plasmas
      PubDate: 2023-04-10T04:27:04Z
      DOI: 10.1063/5.0139276
       
  • The calculations of thermophysical properties of low-temperature indium
           plasma

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      Authors: E. M. Apfelbaum
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      A model for calculation of thermophysical properties (pressure, internal energy, electrical and thermal conductivities, and thermal power) of low-temperature indium plasma is developed at the temperatures 8–100 kK and densities less than 9 g/cm3. It is constructed on the basis of a chemical approach and a relaxation time approximation. The former allows us to obtain the chemical (ionic) composition of indium plasma together with the other thermodynamical values. There have not been any published data concerning these properties in this area for indium plasma up until now, excluding for the semi-empirical models. The area of applicability of the present model has also been estimated. The fitting analytical relations for calculated values, which can be used in practical applications, are constructed.
      Citation: Physics of Plasmas
      PubDate: 2023-04-10T04:27:01Z
      DOI: 10.1063/5.0144465
       
  • An improved Darwin approximation in the classical electromagnetism

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      Authors: Takashi Shiroto
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Darwin approximation, a non-relativistic submodel of the Maxwell's equations, has been used for theoretical and computational investigations of magnetized plasmas. In this short paper, an improved Darwin approximation is proposed, which is applicable not only to the Coulomb gauge but also to the Lorenz counterpart. The proposed approximation exactly satisfies the conservation of charge, momentum, and energy under the use of the Lorenz and Coulomb gauges.
      Citation: Physics of Plasmas
      PubDate: 2023-04-07T02:39:06Z
      DOI: 10.1063/5.0138048
       
  • Developing characteristics of the positive streamer in water with
           microsecond pulse voltage

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      Authors: Yongsheng Wang, Yang Meng, Wenyong Jin, Mingbin Peng, Weidong Ding
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Underwater discharge is the typical method used to generate plasma in a liquid phase environment and is employed in many engineering applications. This study analyzes the formation and development process of the positive streamer in water under microsecond voltage. The effects of voltage amplitude, liquid conductivity, and the presence of bubbles on the underwater discharge characteristics are analyzed by establishing a two-dimensional finite element simulation model of a needle-plate gap. The simulation results show that the electron density of the streamer in water can reach 1023 m−3, and as the applied voltage amplitude increases, the development speed of the streamer increases and the head of the stream bifurcates. Moreover, when the conductivity of the water is high, the development speed of the streamer and the density of charged particles increase. Furthermore, the presence of bubbles significantly impacts the development of the discharge morphology, causing the channel to have multiple bifurcations.
      Citation: Physics of Plasmas
      PubDate: 2023-04-07T02:39:05Z
      DOI: 10.1063/5.0140683
       
  • Analytic insights into nonlocal energy transport: Steady state Fokker
           Planck theory in arbitrary Z plasmas

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      Authors: Wallace Manheimer
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The generation of energetic electrons in laser fusion in an important issue. The electrons may either arise from a laser plasma instability, or from the uncoupled high temperature tail of a Maxwellian distribution. To study these in a laser fusion context, it is important to find a method accurate enough to be useful, and simple enough to be incorporated into a radiation hydrodynamics numerical simulation, the main workhorse for studying the laser fusion target. That is why analytic insights become important, they allow one to simplify the Fokker Planck theory so that a solution of it can be incorporated into a radiation hydrodynamic simulation. This work develops and analyzes a steady state Fokker Planck theory for plasmas of arbitrary Z. It develops a method of solving the simplified Fokker Planck method with a technique called sparse eigenfunction analysis. This method appears to work reasonably well when compared to the experimental results from the Rochester/NIF on plastic spherical targets with and without a silicon layer.
      Citation: Physics of Plasmas
      PubDate: 2023-04-07T02:37:05Z
      DOI: 10.1063/5.0131841
       
  • On the force exerted on a non-spherical dust grain from homogeneous
           magnetized plasma

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      Authors: S. I. Krasheninnikov
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      It is shown that stationary non-spherical dust grains immersed into stationary magnetized plasma can experience the [math] force due to electric current flowing through the grain. The electric current can be caused by different patterns of electron and ion fluxes impinging on the grain.
      Citation: Physics of Plasmas
      PubDate: 2023-04-07T02:37:04Z
      DOI: 10.1063/5.0147349
       
  • Response to “Comment on ‘Arbitrary amplitude ion-acoustic
           supersolitons in negative ion plasmas with two-temperature superthermal
           electrons’” [Phys. Plasmas 30, 044701 (2022)]

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      Authors: Kishan Kumar, M. K. Mishra
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.

      Citation: Physics of Plasmas
      PubDate: 2023-04-06T05:04:11Z
      DOI: 10.1063/5.0142902
       
  • Comment on “Arbitrary amplitude ion-acoustic supersolitons in negative
           ion plasmas with two-temperature superthermal electrons” [Phys. Plasmas
           29, 092101 (2022)]

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      Authors: Steffy Sara Varghese, Frank Verheest, Ioannis Kourakis
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In a recent paper, “Arbitrary amplitude ion-acoustic supersolitons in negative ion plasmas with two-temperature superthermal electrons” [Phys. Plasmas 29, 092101 (2022)], Kumar and Mishra deal with the study of ion-acoustic solitary and supersolitary waves in a four-component plasma consisting of positive ions and negative ions along with two temperature superthermal electrons. Unfortunately, the reported results are incorrect.
      Citation: Physics of Plasmas
      PubDate: 2023-04-06T05:02:30Z
      DOI: 10.1063/5.0138474
       
  • Imaginary-time correlation function thermometry: A new, high-accuracy and
           model-free temperature analysis technique for x-ray Thomson scattering
           data

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      Authors: Tobias Dornheim, Maximilian P. Böhme, David A. Chapman, Dominik Kraus, Thomas R. Preston, Zhandos A. Moldabekov, Niclas Schlünzen, Attila Cangi, Tilo Döppner, Jan Vorberger
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The accurate interpretation of experiments with matter at extreme densities and pressures is a notoriously difficult challenge. In a recent work [Dornheim et al., Nat. Commun. 13, 7911 (2022)], we have introduced a formally exact methodology that allows extracting the temperature of arbitrary complex materials without any model assumptions or simulations. Here, we provide a more detailed introduction to this approach and analyze the impact of experimental noise on the extracted temperatures. In particular, we extensively apply our method both to synthetic scattering data and to previous experimental measurements over a broad range of temperatures and wave numbers. We expect that our approach will be of high interest to a gamut of applications, including inertial confinement fusion, laboratory astrophysics, and the compilation of highly accurate equation-of-state databases.
      Citation: Physics of Plasmas
      PubDate: 2023-04-06T04:54:30Z
      DOI: 10.1063/5.0139560
       
  • Time-dependent saturation and physics-based nonlinear model of cross-beam
           energy transfer

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      Authors: L. Yin, T. B. Nguyen, G. Chen, L. Chacon, D. J. Stark, L. Green, B. M. Haines
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The nonlinear physics of cross-beam energy transfer (CBET) for multi-speckled laser beams is examined using large-scale particle-in-cell simulations for a range of laser and plasma conditions relevant to indirect-drive inertial confinement fusion (ICF) experiments. The time-dependent growth and saturation of CBET involve complex, nonlinear ion and electron dynamics, including ion trapping-induced enhancement and detuning, ion acoustic wave (IAW) nonlinearity, oblique forward stimulated Raman scattering (FSRS), and backward stimulated Brillouin scattering (BSBS) in a CBET-amplified seed beam. Ion-trapping-induced detuning of CBET is captured in the kinetic linear response by a new δf-Gaussian-mixture algorithm, enabling an accurate characterization of trapping-induced non-Maxwellian distributions. Ion trapping induces nonlinear processes, such as changes to the IAW dispersion and nonlinearities (e.g., bowing and self-focusing), which, together with pump depletion, FSRS, and BSBS, determine the time-dependent nature and level of CBET gain as the system approaches a steady state. Using VPIC simulations at intensities at and above the onset threshold for ion trapping and the insight from the time-dependent saturation analyses, we construct a nonlinear CBET model from local laser and plasma conditions that predicts the CBET gain and the energy deposition into the plasma. This model is intended to provide a more accurate, physics-based description of CBET saturation over a wide range of conditions encountered in ICF hohlraums compared with linear CBET gain models with ad hoc saturation clamps often used in laser ray-based methods in multi-physics codes.
      Citation: Physics of Plasmas
      PubDate: 2023-04-05T11:33:23Z
      DOI: 10.1063/5.0134867
       
  • Publisher's Note: “First graded metal pushered single shell capsule
           implosions on the National Ignition Facility” [Phys. Plasmas 29, 052707
           (2022)]

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      Authors: E. L. Dewald, S. A. MacLaren, D. A. Martinez, J. E. Pino, R. E. Tipton, D. D.-M. Ho, C. V. Young, C. Horwood, S. F. Khan, E. P. Hartouni, M. S. Rubery, M. Millot, A. R. Vazsonyi, S. Vonhof, G. Mellos, S. Johnson, V. A. Smalyuk, F. Graziani, E. R. Monzon, R. Tommasini, D. Alessi, S. Ayers, G. N. Hall, J. Holder, D. Kalantar, A. J. MacKinnon, J. Okui, M. Prantil, J.-M. Di Nicola, T. Lanier, A. Thomas, S. Yang, H. W. Xu, H. Huang, J. Bae, C. W. Kong, N. Rice, Y. M. Wang, P. Volegov, M. S. Freeman, C. Wilde
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.

      Citation: Physics of Plasmas
      PubDate: 2023-04-05T11:33:22Z
      DOI: 10.1063/5.0151533
       
  • Numerical simulation of the large-gap and small-gap pre-ionized
           direct-current glow discharges in atmospheric helium

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      Authors: Zaihao Liu, Yinghua Liu, Shuang Ran, Boping Xu, Peiqi Yin, Jing Li, Yishan Wang, Wei Zhao, Hui Wang, Jie Tang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      A one-dimensional self-consistent fluid model was employed to comparatively investigate the influence of pre-ionization on the helium direct-current glow discharge in the large gap and the small gap at atmospheric pressure. For the large-gap and small-gap discharges, the negative glow space and the cathode fall layer are both offset to the cathode with the increase in pre-ionization, which is mainly ascribed to the decrease in charged particle density in the original negative glow space as a result of the increased probability of collision and recombination between ions and electrons, and the new balance between the positive and negative charges established at the distance closer to the cathode. The electron density tends to grow in the negative glow space due to the elevated pre-ionization, while the ion density exhibits an overall downward tendency in the cathode fall layer because the increase in secondary electrons produces more newly born electrons that neutralize more ions via the recombination reaction. Thanks to the pre-ionization, a significant reduction of sustaining voltage and discharge power is obtained in both the large-gap and small-gap discharges. A remarkable characteristic is that the absent positive column in the small-gap discharge comes into being again due to the pre-ionization. Moreover, with the increase in the pre-ionization level, the potential fall shifts from the cathode fall layer to the positive column in the large-gap discharge, while it is always concentrated in the cathode fall layer in the small-gap discharge.
      Citation: Physics of Plasmas
      PubDate: 2023-04-05T11:03:04Z
      DOI: 10.1063/5.0138129
       
  • Spatial distribution modulation of laser-accelerated charged particles
           with micro-tube structures

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      Authors: Q. S. Wang, C. Y. Qin, H. Zhang, S. Li, A. X. Li, N. W. Wang, X. M. Lu, J. F. Li, R. J. Xu, C. Wang, X. Y. Liang, Y. X. Leng, B. F. Shen, L. L. Ji
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We present experimental studies on the spatial distribution of charged particles using a linearly polarized femtosecond laser interacting with a micro-structure target composed of micro-tube structure and planar foil. For protons, a six-lobed structure was observed in the low-energy region, while a smaller angular divergence was measured in the high-energy region. Electron distribution exhibits a circular distribution at low energies and double-lobed structure at high energies. These results are well reproduced by 3D particle-in-cell simulations, showing that the profile of electrons driven by a laser pulse is manipulated by the micro-tube structure, which maps into the spatial distribution of protons via a strong charge separation field. These results demonstrate the effect of micro-structures on laser-driven particle sources and provide a possible approach for spatial manipulation of the particle beams.
      Citation: Physics of Plasmas
      PubDate: 2023-04-05T11:03:03Z
      DOI: 10.1063/5.0138179
       
  • Low-frequency shear Alfvén waves at DIII-D: Theoretical interpretation of
           experimental observations

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      Authors: Ruirui Ma, W. W. Heidbrink, Liu Chen, Fulvio Zonca, Zhiyong Qiu
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The linear properties of the low-frequency shear Alfvén waves such as those associated with the beta-induced Alfvén eigenmodes (BAEs) and the low-frequency modes observed in reversed-magnetic-shear DIII-D discharges [W. Heidbrink et al., Nucl. Fusion 61, 066031 (2021)] are theoretically investigated and delineated based on the theoretical framework of the general fishbone-like dispersion relation (GFLDR). By adopting representative experimental equilibrium profiles, it is found that, even though both modes are predominantly of Alfvénic polarization, the low-frequency mode is a reactive unstable mode with weak coupling to the energetic particles, while the BAE involves a dissipative instability due to resonant excitation by the energetic ions. Thus, the low-frequency mode is more appropriately called a low-frequency Alfvén mode (LFAM). Moreover, the ascending frequency spectrum patterns of the experimentally observed BAEs and LFAMs can be theoretically reproduced by varying qmin and also be well interpreted based on the GFLDR. The present analysis illustrates the solid predictive capability of the GFLDR and its practical usefulness in enhancing the interpretative capability of both experimental and numerical simulation results.
      Citation: Physics of Plasmas
      PubDate: 2023-04-05T11:03:01Z
      DOI: 10.1063/5.0141186
       
  • Development of the neutral model in the nonlinear MHD code JOREK:
           Application to E × B drifts in ITER PFPO-1 plasmas

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      Authors: S. Q. Korving, G. T. A. Huijsmans, J.-S. Park, A. Loarte
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The prediction of power fluxes and plasma-wall interactions impacted by MHD processes during ITER operation [disruption, Edge Localized Modes (ELMs), 3D magnetic fields applied for ELM control, etc.] requires models that include an accurate description of the MHD processes themselves, as well as of the edge plasma and plasma-wall interaction processes. In this paper, we report progress on improving the edge plasma physics models in the nonlinear extended MHD code JOREK, which has capabilities to simulate the MHD response of the plasma to the applied external 3D fields, disruptions and ELMs. The extended MHD model includes E × B drifts, diamagnetic drifts, and neoclassical flows. These drifts can have large influences, on e.g., divertor asymmetries. Realistic divertor conditions are important for impurity sputtering, transport, and their effect on the plasma. In this work, we implemented kinetic and fluid neutral physics modules, investigated the influence of poloidal flows under divertor conditions in the ITER PFPO-1 (1.8T/5MA) H-mode plasma scenario, and compared the divertor plasma conditions and heat flux to the wall for both the fluid and kinetic neutral model (in JOREK) to the well-established 2D boundary plasma simulation code suite SOLPS-ITER. As an application of the newly developed model, we investigated time-dependent divertor solutions and the transition from attached to partially detached plasmas. We present the formation of a high-field-side high-density-region and how it is driven by poloidal E × B drifts.
      Citation: Physics of Plasmas
      PubDate: 2023-04-05T10:50:50Z
      DOI: 10.1063/5.0135318
       
  • Full-f gyrokinetic simulations of Ohmic L-mode plasmas in linear and
           saturated Ohmic confinement regimes

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      Authors: Y. Idomura, G. Dif-Pradalier, X. Garbet, Y. Sarazin
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Two time slices in linear and saturated Ohmic confinement (LOC and SOC) regimes in a Tore Supra Ohmic L-mode discharge are analyzed using nonlinear global full-f gyrokinetic simulations, and qualitative features of the LOC–SOC transition are reproduced. The exhaust of carbon impurity ions is caused by ion mixing, which is driven by the toroidal field stress. The intrinsic rotation develops in the opposite direction between the LOC and SOC phases, which is characterized by different features of the mode asymmetry between trapped electron modes (TEMs) in the LOC phase and ion temperature gradient-driven modes in the SOC phase, leading to the change of the profile shear stress. Here, the mode asymmetry or the ballooning angle depends not only on the profile shear and the Er shear but also on the radial electric field Er itself. The energy fluxes of electrons and deuterium ions are dominant in the LOC and SOC phases, respectively, and the ratio of the energy confinement time between the two phases agree with the experimental value. Turbulent frequency spectra are characterized by quasi-coherent modes (QCMs) and broad-band spectra in the LOC and SOC phases, respectively. The QCMs are produced by a split of the toroidal mode number spectra of TEMs induced by the Doppler shift of poloidal E × B rotation due to Er, which is sustained in the electron diamagnetic direction by the ripple induced counter-current rotation, and enhanced by higher temperature in the LOC phase.
      Citation: Physics of Plasmas
      PubDate: 2023-04-05T10:50:46Z
      DOI: 10.1063/5.0127346
       
  • From a single dust grain to basic thermodynamics

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      Authors: Dietmar Block, Sören Wohlfahrt, Frank Wieben
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      This contribution summarizes recent experiments in dusty plasmas and puts their results into context. The aim is to discuss the fundamental question whether a dusty plasma can be regarded as a model system for strong coupling and whether the treatment as a one-component plasma is a good and valid approximation.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:15:20Z
      DOI: 10.1063/5.0144309
       
  • An improved resistance model of positive subsonic plasma channels in water

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      Authors: He Zhang, Yi Liu, Hongji Liu, Youlai Xu, Hua Li, Fuchang Lin
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The subsonic plasma channel and water can be regarded as series resistors in the pre-breakdown stage of sub-millisecond pulsed discharge in conductive water. An improved resistance model of the positive subsonic plasma channel is proposed. The gap resistance and the morphology of the bubble cluster and the plasma channel inside it are obtained from the electrical measurement and optical observation, respectively. The resistance of the plasma channel in the strong-ionization stage is calculated using the small-current arc resistance model. The improved model of the water resistance is established by analyzing the relationship between its equivalent cross-sectional area and its length in an uneven electric field. The resistance of the plasma channel in the weak-ionization stage is calculated. The resistance, voltage, and energy in the gap are analyzed based on the improved resistance model. The plasma channel's resistance is far less than the water resistance. The low voltage drop in the plasma channel leads to a high electric potential in the plasma channel's head, which is conducive to the plasma channel's development. 97% of the total energy in the pre-breakdown stage is consumed by the water resistor. The improved resistance model is helpful to supplement the development mechanism of the sub-millisecond pulsed discharge in water.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:15:17Z
      DOI: 10.1063/5.0128080
       
  • On power and fundamental resistance relations in symmetric RF CCPs by
           simulating simplified nonlinear circuits

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      Authors: M. Q. Du, Z. F. Ding
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Voltage and current measured from radio frequency (RF) capacitively coupled plasmas (CCPs) are basic data, from which various powers and impedances are subsequently calculated via fast Fourier transform to gain deep insight into RF CCPs. The specific values of these parameters depend on the nonlinearity of RF CCPs and the interaction with the external circuit, but the relation between harmonic powers and that among the fundamental resistances are not known. These questions are investigated via Multisim software by simplifying the symmetric RF CCP with the nonlinear circuit consisting of a linear resistor and a nonlinear capacitor. The results show that the calculated total RF power is accurately equal to that dissipated by the resistor in discharge. However, it is not true for the fundamental power and harmonic one. The fundamental resistance calculated at the external electrode, which was previously proposed as the plasma resistance, is higher than the latter. The conversion between the fundamental and harmonic powers in the nonlinear ideal capacitor of RF CCPs is the origin of the obtained abnormal feature. In comparison, the plasma resistance calculated from the total RF power and current is unaffected by harmonics and is, thus, more credible, despite that this method requires an assumption of constant transient plasma resistance.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:13:50Z
      DOI: 10.1063/5.0134006
       
  • Sensitivity of synchrotron radiation to the superthermal electron
           population in mildly relativistic plasma

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      Authors: M. E. Mlodik, V. R. Munirov, T. Rubin, N. J. Fisch
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Synchrotron radiation has markedly different behavior in [math] and in [math] plasma. We show that high-energy electrons that occupy the tail of velocity distribution function have disproportionate impact on power loss of [math] plasma. If electrons with energy more than cutoff energy are redistributed while keeping the Maxwellian distribution function below cutoff energy intact, both emission and absorption of synchrotron radiation act to decrease the lost power. These novel radiation transport effects in non-equilibrium plasma suggest large utility in the deconfinement of high-energy electrons to reduce synchrotron radiation in applications where the radiation is deleterious.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:13:47Z
      DOI: 10.1063/5.0140508
       
  • Absolute and global instabilities driven by Cherenkov interaction between
           magnetized electron beam and spoof surface plasmon polaritons

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      Authors: Y. Annaka, K. Ogura, M. Ito
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In this study, we examine absolute and global instabilities driven by the Cherenkov interaction between a magnetized electron beam and spoof surface plasmon polaritons (SPPs) with an azimuthal mode number m. The absolute and global instabilities are induced in long and short lengths of the cylindrical corrugated waveguides (CCWs), respectively. The temporal and spatial growth rates have different dominant modes of spoof SPPs that, respectively, affect the absolute and global instabilities. In the experiment, the G-band radiation, which corresponds to the dominant mode in the spatial growth rate, is observed with the short length CCW. In the long CCW, the G-band radiation vanishes because the dominant mode in the temporal growth rate has lower frequency than the G-band cutoff frequency of the detecting system. Our results demonstrate that the instability and the multimode radiation are changed by the length of the CCW.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:12:48Z
      DOI: 10.1063/5.0139713
       
  • Radiation reaction and its impact on plasma-based energy-frontier
           colliders

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      Authors: Hossein Saberi, Guoxing Xia, Mohammad R. Islam, Linbo Liang, Can Davut
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Energy-frontier TeV colliders based on plasma accelerators are attracting much attention due to the recent achievements in multi-stage laser acceleration as well as the remarkable advances in electron- and proton-driven plasma accelerators. Such colliders may suffer a fundamental energy loss due to the radiation reaction (RR) effect, as the electrons lose energy through betatron radiation emission. Although the RR may not be critical for low-energy accelerators, it will exert limitations on TeV-class plasma-based colliders that need to be considered. In this paper, we have provided an extensive study of the RR effect in all pathways toward such colliders, including multi-stage plasma acceleration driven by the state-of-the-art lasers and the relativistic electron beam as well as the single-stage plasma acceleration with the energetic proton beams available at the CERN accelerator complex. A single-particle Landau–Lifschitz approach is used to consider the RR effect on an electron accelerating in the plasma blow-out regime. The model determines the boundaries where RR plays an energy limiting role on such colliders. The energy gain, the radiation loss, and the validity of the model are numerically explored.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:12:47Z
      DOI: 10.1063/5.0140525
       
  • Dynamical process in the stagnation stage of the double-cone ignition
           scheme

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      Authors: K. Fang, Y. H. Zhang, Y. F. Dong, T. H. Zhang, Z. Zhang, X. H. Yuan, Y. T. Li, J. Zhang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In the double-cone ignition scheme, two deuterium–tritium shells in a pair of head-on Au cones are compressed and accelerated spherically [Zhang et al., Philos. Trans. R. Soc. A. 378 (2184), 20200015 (2020)]. The high-speed plasma jets from the cone tips collide and form a stagnating plasma with a higher density during the stagnation stage, preheating the plasma by the Coulomb potential. The preheated plasma is then rapidly heated up further to the ignition temperature by fast electrons generated by a powerful laser pulse of 10 ps. The conditions of the stagnating plasma strongly affect the fast-heating efficiency and consequently the success of ignition. In order to understand dynamical process in the stagnation stage, a special experimental campaign was conducted, where the evolution of the stagnating plasma was diagnosed through the temporal resolved self-emission signals. The spatial-temporal distributions of temperature and density of the colliding plasma were analyzed by the Abel inversion algorithm and the Legendre polynomial fitting. The stagnation period was found to be about 300 ps, the temperature of the core area of the stagnated plasma was between 340 and 390 eV, while the aspect ratio of the colliding plasma was about 0.78.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:10:30Z
      DOI: 10.1063/5.0139659
       
  • Hybrid ablation–expansion model for laser interaction with
           low-density foams

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      Authors: L. Hudec, A. Gintrand, J. Limpouch, R. Liska, S. Shekhanov, V. T. Tikhonchuk, S. Weber
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      A sub-grid foam model is developed to describe numerically a sequence of processes transforming solid elements in the foam into a hot plasma under the energy deposition by lasers. We account for three distinct processes: accurate laser energy absorption and scattering on the sub-wavelength cylindrical solid elements, expansion of the foam element due to the energy deposition in its volume, and ablation of the solid element due to the energy deposition on its surface. The foam element dynamics is modeled via a self-similar isothermal expansion combined with a stationary ablation model, and it is described by a set of ordinary differential equations. The microscopic single pore model is incorporated in the macroscopic hydrodynamic codes, and numerical simulations show a good agreement with available experimental data.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:10:28Z
      DOI: 10.1063/5.0139488
       
  • Disruption halo current rotation scaling on Alcator C-Mod and HBT-EP

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      Authors: A. R. Saperstein, R. A. Tinguely, R. S. Granetz, J. P. Levesque, M. E. Mauel, G. A. Navratil
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Asymmetric halo currents (HCs) can exert large net forces on the vacuum vessel and other components during disruptions on tokamaks. The displacements caused by these forces can then be amplified if these asymmetric forces rotate at frequencies resonant with the vessel. This paper reports on the investigation of a recently proposed scaling law for the disruption HC rotation frequency [Saperstein et al., “Halo current rotation scaling in post-disruption plasmas,” Nucl. Fusion 62, 026044 (2022)] that combines measurements on Alcator C-Mod with those on HBT-EP. We find that a new non-circular version of the scaling law [[math]] takes into consideration the dependence of frot on the poloidal structure of the MHD instability (m) driving the asymmetry and describes the disruption-averaged rotation frequency on C-Mod. Disruption rotation is also found to be insensitive to the vertical position and impurity content of the plasma at the onset of the disruption. However, a stagnation in the time evolution of frot is occasionally observed. Observations are consistent with the dominance of poloidal rotation during the disruption, which is motivated by the poloidal drift nature of the scaling law.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:06:48Z
      DOI: 10.1063/5.0140867
       
  • Ideal MHD induced temperature flattening in spherical tokamaks

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      Authors: S. C. Jardin, N. M. Ferraro, W. Guttenfelder, S. M. Kaye, S. Munaretto
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      This paper extends the analysis first presented in Jardin et al. [Phys. Rev. Lett. 128, 245001 (2022)] to more thoroughly examine the stability of spherical torus equilibrium to ideal magnetohydrodynamic (MHD) infernal modes and their nonlinear consequences. We demonstrate that in a 3D resistive magnetohydrodynamic (MHD) simulation of a NSTX discharge, anomalous transport can occur due to these instabilities. We generate a family of equilibrium of differing β and use this to show that these instabilities could explain the experimentally observed flattening of the electron temperature profile at modest β. The modes studied in this paper are found to occur with poloidal mode number m and toroidal mode number n when the ratio m/n is in the range of 1.2–1.5, when the central safety factor is in this range or slightly lower, and when the central region has very low magnetic shear. Our analysis gives some insight as to why the unstable linear growth rates are oscillatory functions of the toroidal mode number n. We present a simulation of an initially stable configuration that passes through a stability boundary at a critical β as it is heated. We also show that a particular NSTX discharge is unstable to these modes over a timescale of several hundred ms. We conclude that these modes must be taken into account when performing predictive modeling. An appendix shows that similar modes can be found in [math] tokamaks for certain q-profiles and β values.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:06:47Z
      DOI: 10.1063/5.0141858
       
  • Toroidal vs cylindrical analytical description of the magnetic field
           outside the elongated evolving plasma in tokamaks

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      Authors: V. D. Pustovitov, N. V. Chukashev
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In the plasma equilibrium theory, Gajewski's analytical expression [Gajewski, Phys. Fluids 15, 70 (1972)] for the poloidal magnetic flux [math] outside the plasma is known. It was obtained as a solution of the two-dimensional Laplace equation outside an infinite straight cylinder with an elliptical cross section and a uniform current density [math]. An example of its use for analysis of static configurations is given in the study by Porcelli and Yolbarsop [Phys. Plasmas 26, 054501 (2019)]. Here, we consider the question of its applicability in dynamic problems including, for example, the current quench (CQ) or vertical displacement event (VDE), when the electromagnetic response of the vacuum vessel to the plasma magnetic field evolution has to be accounted for. It is shown that the mentioned cylindrical model does not provide enough information for calculation of the current induced in the wall. Mathematically, this manifests itself in the fact that Gajewski's expression contains an indefinite constant of integration [math] (hereinafter it is [math] at the plasma boundary), which, in analytical applications, is replaced either by zero or by a value that makes [math] on the magnetic axis. This does not affect the magnitude of the magnetic field [math], but it would incorrectly give the electric field at [math]. To eliminate this shortcoming, an additional block of calculations in the toroidal geometry is needed. Here, the problem is solved analytically. The resulting final expression with [math] well-defined in the toroidal configuration also includes the effects of the Shafranov's shift and inhomogeneity of [math]. The proposed extensions allow generalization of the earlier results to a wider area and cover such events as CQ or VDE.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:04:51Z
      DOI: 10.1063/5.0142432
       
  • On the impact of electric field fluctuations on microtearing turbulence

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      Authors: M. Hamed, M. J. Pueschel, J. Citrin, M. Muraglia, X. Garbet, Y. Camenen
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The magnetic drift and the electric potential play an important role in microtearing destabilization by increasing the growth rate of this instability in the presence of collisions, while in electrostatic plasma micro-turbulence, zonal electric potentials can have a strong impact on turbulent saturation. A reduced model has been developed, showing that the Rechester–Rosenbluth model is a good model for the prediction of electron heat diffusivity by microtearing turbulence. Here, nonlinear gyrokinetic flux-tube simulations are performed in order to compute the characteristics of microtearing turbulence and the associated heat fluxes in tokamak plasmas and to assess how zonal flows and zonal fields affect saturation. This is consistent with a change in saturation mechanism from temperature corrugations to zonal field- and zonal flow-based energy transfer. It is found that removing the electrostatic potential causes a flux increase, while linearly stabilization is observed.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:04:47Z
      DOI: 10.1063/5.0104879
       
  • Hot electron scaling for two-plasmon decay in ICF plasmas

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      Authors: E. Rovere, A. Colaïtis, R. K. Follett, A. Casner
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We present a parametric scaling of hot electron (HE) generation at quarter critical density from the two-plasmon decay process. The study is conducted with the laser plasma simulation environment code, considering Langmuir decay instabilities (LDI) and laser pump depletion in 2D. The parameter scan is conducted as a function of electron temperature, ion–electron temperature ratio, drive strength, and density scale length. The scaling shows an hot electron (HE) conversion fraction up to 40%, HE fluxes up to [math] [math], and average temperatures in the range of 30 to 100 keV. The electron angular distributions exhibit two main regions: the plasma “bulk,” characterized by homogeneous emission, up to energies of [math] keV depending on the individual laser–plasma conditions, and a HE tail after [math] keV. The mid-energy electrons are homogeneously emitted toward the end of the plasma bulk and acquire energy through electron plasma wave (EPW) Landau damping from Langmuir wave collapse and LDI cascade. The HE tail has electrons emitted in the forward direction and at low divergence, due to turbulence and EPW Landau damping from multi-staged acceleration. Finally, the laser power transmitted through the quarter critical region reaches values from [math] down to [math] for increasing HE generation, with absorption due to EPW collisional damping in the range of [math].
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:02:51Z
      DOI: 10.1063/5.0128052
       
  • Dynamic of shock–bubble interactions and nonlinear evolution of ablative
           

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      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      It is believed that isolated defects within the capsule (e.g., void, high-density inclusion) can be one of the essential factors for implosion performance degradation by seeding hydrodynamic instabilities in implosions. Nonetheless, a systematic study on how the isolated defects evolve and why they are not stabilized by ablation given the length scale comparable with the typical cutoff wavelength is still lacking. This paper addresses the above concerns by looking into a simplified model where a planar shell (without convergent geometry) is driven by laser direct-drive, with a single defect (low/high density) of micrometer or sub-micrometer scale residing at different locations inside. The underlying dynamics of two key physical processes are analyzed, i.e., the shock–bubble interactions as well as the subsequent nonlinear evolution of ablative hydrodynamic instabilities initiated by the direct interaction of the deformed defect and ablation front, revealing that compressibility and baroclinic effects drive vorticity production during the interactions between the shock wave and the isolated defect. In the “light-bubble” case, the vortex pair generated in the first process is further strengthened by the laser ablation. Hence, a directed flow is formed in companion with the persistent flow entering the bubble of the surrounding ablator. The bubble exhibits a remarkable growth both laterally and deeply, seriously threatening the shell's integrity. The positive feedback mechanism of the vortex pair is absent in the “heavy-bubble” counterpart, and the ablation stabilization manifested itself in the reduction of spike amplitude. A systematic study of localized perturbation growth as a function of defect placement, size, and preheating intensity is presented.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T02:02:47Z
      DOI: 10.1063/5.0137856
       
  • Relativistic analysis of upper hybrid wave propagation and trapping

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      Authors: S. K. Hansen, S. K. Nielsen, J. Stober
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We investigate the impact of relativistic effects on upper hybrid (UH) waves in plasmas with thermal electrons, particularly focusing on modifications of the conditions under which UH wave trapping and related low-threshold parametric decay instabilities (PDIs) may occur. A moderately relativistic (MR) dispersion relation for UH waves, valid for electron temperatures up to 25 keV and wave frequencies up to twice the electron cyclotron frequency, is obtained from previous results and shown to reduce to the warm non-relativistic result commonly used for PDI studies at low electron temperatures. The conditions under which MR UH waves propagate are then determined and compared with warm and cold plasma theory, showing a general increase in the electron density and background magnetic field strength at which the UH resonance occurs for finite electron temperatures. We next investigate the impact of the MR corrections on the possibility of UH wave trapping for X-mode electron cyclotron resonance heated (ECRH) plasmas at the ASDEX Upgrade tokamak and scaled versions of the ASDEX Upgrade parameters with core electron temperatures resembling those expected in ITER X-mode ECRH plasmas. The MR UH wave trapping conditions are virtually unchanged for ASDEX Upgrade relative to warm theory, due to the low electron temperatures, while potentially important differences between warm and MR theory exist for ITER-like core electron temperatures; cold theory is found to be insufficient in both cases. Finally, the MR dispersion relation is shown to qualitatively reproduce the PDI thresholds from warm theory for previously studied ASDEX Upgrade cases.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T01:59:49Z
      DOI: 10.1063/5.0138249
       
  • Data processing techniques for ion and electron-energy distribution
           functions

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      Authors: A. Caldarelli, F. Filleul, R. W. Boswell, C. Charles, N. J. Rattenbury, J. E. Cater
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Retarding field energy analyzers and Langmuir probes are routinely used to obtain ion and electron-energy distribution functions (IEDF and EEDF). These typically require knowledge of the first and second derivatives of the current–voltage characteristics, both of which can be obtained using analog and numerical techniques. A frequent problem with electric-probe plasma diagnostics is the noise from the plasma environment and measurement circuits. This poses challenges inherent to differentiating noisy signals, which often require prior filtering of the raw current–voltage data before evaluating the distribution functions. A review of commonly used filtering and differentiation techniques is presented. It covers analog differentiator circuits, polynomial fitting (Savitzky–Golay filter and B-spline fitting), window filtering (Gaussian and Blackman windows) methods as well as the AC superimposition and Gaussian deconvolution routines. The application of each method on experimental datasets with signal-to-noise ratios ranging from 44 to 66 dB is evaluated with regard to the dynamic range, energy resolution, and signal distortion of the obtained IEDF and EEDF as well as to the deduced plasma parameters.
      Citation: Physics of Plasmas
      PubDate: 2023-04-04T01:59:47Z
      DOI: 10.1063/5.0133840
       
  • Dusty plasmas above the sunlit surface of Mercury

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      Authors: S. I. Popel, A. P. Golub', L. M. Zelenyi
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Above the sunlit surface of Mercury, the properties and formation of dusty plasmas are investigated. It is demonstrated that the dusty plasmas are formed for subsolar angles exceeding approximately 76° due to photoelectric and electrostatic processes. As a result, the dusty plasmas are present in the polar regions of Mercury, characterized by latitudes of about 70° and above. The formation of dusty plasmas is also possible for lower latitudes, but only where the surface profile allows it. Plasmas above the sunlit surface of Mercury consist, in particular, of photoelectrons, electrons, and ions of the solar wind, and also charged dust particles. The distribution functions of photoelectrons near the surface of Mercury, as well as the altitude dependences of the number densities of dust particles, their charges and sizes, as well as electric fields, are obtained. The calculations are carried out which correspond to the position of Mercury at aphelion and perihelion of its orbit for the situations of dusty plasma location in the vicinity of magnetic poles of Mercury and in other regions. It is shown that there are qualitative differences between the dusty plasma systems of Mercury and the Moon related to the fact that Mercury has a magnetosphere and Mercury's orbit is one of the most eccentric of all planetary orbits in the Solar System. The effects of magnetic fields can slightly influence the dust particle transport and, correspondingly, the expansion of the region of the existence of dusty plasmas above the surface of Mercury due to the effect of dust particle transport is not so significant as at the Moon. Furthermore, due to the presence of Mercury's magnetosphere, the solar wind is important for the formation of dusty plasmas at Mercury only in the vicinity of the regions of the magnetic poles. In other regions of Mercury, in contrast to the situation at the Moon, the solar wind does not influence significantly the dusty plasma properties. The dusty plasma parameters are different in the cases of aphelion and perihelion of the orbit of Mercury.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:13:30Z
      DOI: 10.1063/5.0142936
       
  • Dynamical commensuration effect in a two-dimensional Yukawa solid
           modulated by periodic substrates

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      Authors: Wenqi Zhu, C. Reichhardt, C. J. O. Reichhardt, Yan Feng
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Transverse depinning dynamics of a periodic-square-substrate modulated two-dimensional dusty plasma solid driven by a constant force in the longitudinal direction are investigated using Langevin dynamical simulations. When the commensuration ratio (the number ratio of particles to substrate potential wells) is increased, there is a nonmonotonic variation of the critical transverse depinning force, and the local maxima and minima of the critical transverse depinning force precisely correspond to the dynamical commensurate and incommensurate conditions, respectively. The dynamical commensuration effect is also clearly visible in the stable one-dimensional channel particle trajectories and the highly ordered structure, while both the particle trajectories and the structure are more disordered under the incommensurate conditions. The nonmonotonic variation of the critical transverse depinning force is attributed to the stability of the lattice structure at specific commensuration ratios.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:13:29Z
      DOI: 10.1063/5.0143008
       
  • The effects of pulse voltage rise time on the nanosecond pulsed breakdown
           of nitrogen spark switch at atmospheric pressure with 3D PIC-MCC model

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      Authors: Yongliang Wang, Junna Li, Ming Jiang, Qisheng Li, Chunan Li, Shiji Li, Haoyan Wang, Aici Qiu
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In this paper, the effects of pulse voltage rise time on the nanosecond pulsed breakdown of the nitrogen spark switch at atmospheric pressure are analyzed. Based on the assumption of initial electrons generation due to the field emission, the simulations are performed using a three-dimensional particle-in-cell, Monte Carlo-collision model for the pulse voltage with a rise time of 40, 60, and 100 ns, respectively. The breakdown experiments of the nitrogen spark switch are carried out for three different rise times. The results obtained are as follows. First, the nanosecond pulsed breakdown of the switch includes the formation and fast propagation of the streamer, which depend on the multiplication of the electron avalanche, and the intense ionization due to photoelectrons and energetic electrons, respectively. Second, with the rise time of pulse voltage increasing, the generation of runaway electrons becomes more difficult and the streamer branches, which are mainly caused by photoionization and captured energetic electrons, become more obvious. Finally, the breakdown time delay of the switch becomes shorter and the breakdown voltage becomes higher at the same pressure for the decreasing rise time of pulse voltage, which is consistent with the measurement results.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:13:28Z
      DOI: 10.1063/5.0138011
       
  • Effects of pulse rise time on electron dynamics properties in
           nitrogen–oxygen mixture under repetitive nanosecond pulses

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      Authors: Chenjie Li, Xinlei Zheng, Yifeng Wang, Shuhan Liu, Zheng Zhao, Jiangtao Li
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The effects of pulse rise time on the temporal evolution of electron energy and density under repetitive nanosecond pulses in atmospheric nitrogen with 100 ppm oxygen impurities are investigated in this paper by a two-dimensional particle-in-cell/Monte Carlo collision model. It is found that the peak value of mean electron energy increases with decreasing pulse rise time in the single pulsed discharge. However, in the repetitive pulsed discharge approximated by pre-ionization, the peak value of mean electron energy no longer varies with the pulse rise time, showing a saturation trend with decreasing pulse rise time. Whether or not pre-ionization is present, the time required for the mean electron energy to reach its peak is approximately equal to the pulse rise time. It is worth noting that the presence of pre-ionization enhances the tracking ability of the mean electron energy to the pulse waveform during the pulse rise edge. Although after the peak of the pulse, the mean electron energy terminates the tracking process to pulse waveform due to the formation of high-density avalanches and even streamers, its energy decay rate gradually decreases with the increase in the pre-ionization density. Therefore, when the pulse repetitive frequency is greatly increased or the pre-ionization density is increased by other means, it is possible to achieve the complete control of the mean electron energy by pulse waveform modulation.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:08:30Z
      DOI: 10.1063/5.0135115
       
  • Nanosecond pulse breakdown in noble gases

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      Authors: P. A. Bokhan, P. P. Gugin, M. A. Lavrukhin, N. Glubokov, D. E. Zakrevsky
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The results of the investigation of the breakdown characteristics of the planar “open” discharge and open discharge with the generation of counter-propagating electron beams under excitation by pulses with nanosecond rise fronts are presented. The amplitude parameters of current and voltage and temporal characteristics of breakdown in helium, neon, and argon were measured. It is demonstrated that the breakdown in the open discharge is characterized by considerably larger electric field strengths at the same development delays as in the avalanche discharge. A similarity criterion based on the photoemission mechanism of electron generation, according to which the discharge development delay is inversely proportional to the squared working gas pressure, is obtained.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:08:28Z
      DOI: 10.1063/5.0138062
       
  • Broadband microwave absorption effects in 2D nitrogen capacitively coupled
           plasma under different operating conditions

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      Authors: Wenchong Ouyang, Qi Liu, Chengbiao Ding, Zhengwei Wu
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In recent years, the interaction of electromagnetic waves (EM) with plasma sources under argon and helium discharges has been extensively studied due to its potential applications in plasma stealth. However, nitrogen, as a more economical discharge gas, has been ignored in terms of its absorption of EM waves and stealth effect. In this work, a numerical calculation model combining two-dimensional capacitively coupled plasma (CCP) fluid model and EM wave model was developed to investigate the plasma uniformity degree and broadband microwave absorption effects in helium and nitrogen CCP. It is concluded that the two-dimensional model in this paper has more accurate and reasonable through comparison with the one-dimensional and experimental results in helium CCP. Nitrogen CCP shows better broadband absorption effects than that of helium, and helium plasma has better uniformity than nitrogen under the same discharge parameters. But the uniformity degree of nitrogen plasma is not much different from that of helium under the same electron density, which means that nitrogen can significantly improve its broadband wave absorption properties to some extent without loss of uniformity degree. Based on the above conclusions, the absorption characteristics of nitrogen CCP under different radio frequency (RF) power and pressure are analyzed. The attenuation effect of nitrogen CCP increases with the increasing RF power, and it is interesting that the influence of pressure on the attenuation of EM waves is not monotonically increasing, and the related mechanism is discussed. Finally, discussion of skin depth under different RF power and pressure validates the above conclusions. The absorption band of nitrogen CCP under the best parameters in this work can reach the X-band, which shows great application potential in plasma stealth.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:06:32Z
      DOI: 10.1063/5.0128430
       
  • Langmuir probe measurements of the secondary electron population across
           the cathodic pre-sheath of a DC argon discharge

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      Authors: Nicholas Ranson, Richard Bowden-Reid, Joe Khachan, Nicolas Claire
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Cylindrical Langmuir probe measurements in a low-pressure DC argon discharge are used to obtain the spatial evolution of ion, cold and hot electron parameters across the cathodic pre-sheath. The cathodic pre-sheath is formed by a stainless steel plate allowed to float negatively with respect to the plasma. The velocity distribution function of the hot electron population in the pre-sheath is shown to be matched by a drifting Maxwellian that thermalizes across it. The source of the hot electron population is hypothesized to arise from secondary electron emission from the plate. A Bayesian estimation routine is proposed to compare and validate different Langmuir probe models as well as calculating the relative uncertainty between models. The results are analyzed using existing pre-sheath theory for which experimental evidence of the spatial influence of energetic electrons is lacking. The data are shown to follow Riemann's pre-sheath model that the ion-neutral mean free path [math] is proportional to the pre-sheath characteristic length l, and that the potential drop [math] with distance x from the sheath/pre-sheath boundary x0 follows [math].
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:06:29Z
      DOI: 10.1063/5.0130291
       
  • Low peak-to-average ratio 850 GHz backward wave oscillator for THz
           communication

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      Authors: Rong Bao, Hongguang Wang, Yongdong Li, Chunliang Liu
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      In sub-THz communication systems, compact, high-power, tunable radiation sources are required. Backward wave oscillators (BWO) have been practical devices for THz communication, but the maximum output power can be several times more than the minimum in the operation frequency range. To obtain the low peak-to-average ratio (LPAR) of the maximum power to the average power, the local maximum output power in the operation frequency range is first found theoretically and verified by particle-in-cell simulation. The LPAR 850 GHz BWO is then proposed. It applies a corrugated rectangular waveguide slow-wave structure, whose geometrical parameters are optimized using a multi-constrained optimization method. The optimized BWO operating in the frequency range from 790  to 882 GHz is simulated by the CST Particle Studio. The device can deliver at least 0.58 W with a LPAR of 1.08 when the conductivity of the slow-wave structure is 5.96 × 107 S/m. For a smaller conductivity of 3 × 107 S/m, the BWO can deliver at least 0.4 W with a LPAR of 1.13.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:03:10Z
      DOI: 10.1063/5.0137486
       
  • Spatiotemporal theory of the sectioned gyro-BWO with the zigzag
           quasi-optical system

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      Authors: E. M. Novak, S. V. Samsonov, A. V. Savilov
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We present the quasi-analytical spatiotemporal theory, which describes the process of establishing generation in a backward-wave gyro-oscillator based on the use of a sectioned quasi-optical system with the zigzag path of the operating wave beam. This theory explains peculiarities (namely, a piecewise character) of changing the operating frequency and power of the output signal in the process of the broadband frequency tuning provided by changing the operating magnetic field. This theory also describes competition of different modes of the system in the process of excitation of auto-oscillators and predicts the possibility for realization of the regime of automodulations of the output power, as well as the regime of formation of a short powerful super-radiant pulse.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:03:08Z
      DOI: 10.1063/5.0140591
       
  • The nonlocal electron heat transport under the non-Maxwellian distribution
           in laser plasmas and its influence on laser ablation

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      Authors: Kai Li, Wen Yi Huo
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The electron heat transport plays an important role in laser driven inertial confinement fusion. For the plasmas created by intense laser, the traditional Spitzer–Härm theory cannot accurately describe the electron heat transport process mainly due to two physical effects. First, the electron distribution function would significantly differ from the Maxwellian distribution because of the inverse bremsstrahlung heating. Second, the long mean free paths of heat carrying electrons relative to the temperature scale length indicate that the electron heat flux has the nonlocal feature. In 2020, we have developed a nonlocal electron heat transport model based on the non-Maxwellian electron distribution function (NM-NL model) to describe the electron heat flux in laser plasmas. Recently, this model is successfully incorporated into our radiation hydrodynamical code RDMG. In this article, we numerically investigated the electron heat flux in laser plasmas, especially the nonlocal feature of heat flux and the influence of the non-Maxwellian distribution. The influence of electron heat transport on laser ablation is also discussed. The simulated plasma conditions based on different electron heat transport models are presented and compared with experiments. Our results show that the nonlocal feature of heat flux and the influence of non-Maxwellian distribution function are considerable in plasmas heated by intense lasers.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:02:09Z
      DOI: 10.1063/5.0130888
       
  • Modeling density effects on electronic configurations in warm dense
           plasmas

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      Authors: Gérald Faussurier
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We present a method to calculate the shift of the K edge in warm dense aluminum. We use the average-atom model and show how to build the energy of an electronic configuration with integer subshell populations and by taking into account the interaction of the bound electrons with the free electrons. We successfully compare our calculation of the spectral opacity with the Henke table for aluminum at solid density and 300 K. We found a redshift of the K edge along the principal Hugoniot consistent with experimental data. We also compute the 2s and 2p edges. We obtain L edge redshifts similar to the K edge redshift.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:02:08Z
      DOI: 10.1063/5.0143549
       
  • Maximum entropy states of collisionless positron–electron plasma in
           a dipole magnetic field

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      Authors: Naoki Sato
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      We are developing a positron–electron plasma trap based on a dipole magnetic field generated by a levitated superconducting magnet to investigate the physics of magnetized plasmas with mass symmetry as well as antimatter components. Such laboratory magnetosphere is deemed essential for the understanding of pair plasmas in astrophysical environments, such as magnetars and blackholes, and represents a novel technology with potential applications in antimatter confinement and the development of coherent gamma-ray lasers. The design of the device requires a preemptive analysis of the achievable self-organized steady states. In this study, we construct a theoretical model describing maximum entropy states of a collisionless positron–electron plasma confined by a dipole magnetic field and demonstrate efficient confinement of both species under a wide range of physical parameters by analyzing the effect of the three adiabatic invariants on the phase space distribution function. The theory is verified by numerical evaluation of spatial density, electrostatic potential, and toroidal rotation velocity for each species in correspondence with the maximum entropy state.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:00:49Z
      DOI: 10.1063/5.0135659
       
  • Experiment with nitrogen seeding at the Globus-M2 tokamak

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      Authors: E. Vekshina, K. Dolgova, V. Rozhansky, E. Kaveeva, I. Senichenkov, P. Molchanov, V. Timokhin, N. Khromov, N. Zhiltsov, N. Bakharev, E. Kiselev, E. Tuhmeneva
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      First experiment with nitrogen seeding has been performed at the compact spherical tokamak Globus-M2. Significant reduction of the electron temperature and the energy flux to the outer lower divertor target has been observed experimentally and reproduced in the modeling with the SOLPS-ITER code.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T10:00:48Z
      DOI: 10.1063/5.0134542
       
  • Simulations of energy deposition of electron cyclotron waves in a
           dipole-confined plasma based on ray trajectory

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      Authors: Hao-Jie Ma, Hua-Sheng Xie, Bo Li
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The energy deposition of electron cyclotron waves in a dipole-confined plasma is investigated for the RT-1 device, specifically including the effects of high-energy electrons and the electron Bernstein wave (EBW) excitation and absorption. Simulations of wave trajectories with various injection locations and angles indicate that the energy deposition of ordinary mode (O-mode) and extraordinary modes (X-mode) is small in low-temperature plasmas. The high-energy electrons in the plasma increase the energy deposition of the X-mode but have little effect on the O-mode. Meanwhile, the energy deposition of the slow X-EBW conversion and O-X-EBW conversion to excite EBW is also discussed. The results show that the converted EBW in an over-dense plasma is easily obtained, but it may not always have efficient energy deposition. Finally, the possible mechanism for the plasma production and heating by using electron cyclotron waves is proposed.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T09:57:52Z
      DOI: 10.1063/5.0133133
       
  • A solution method of slowing-down distribution of energetic particles in
           tokamaks

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      Authors: Yongzhi Dai, Jinjia Cao, Dong Xiang, Junhui Yang
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The eigen equation of pitch-angle distribution derived from the slowing-down distribution equation with an energetic particle source term is solved by using the Legendre series expansion method. An iteration matrix is established when pitch-angle scattering terms become important. The whole pitch-angle region is separated into three parts, two passing regions, and one trapped area. The slowing-down distribution for each region is finally obtained. The method is applied to solve the slowing-down equations with source terms that the pitch-angle distribution is Maxwellian-like, neutral beam injection, and radial drifts. The distribution functions are convergent for each source with different pitch-angle distribution. The method is suitable for solving a kinetic equation that pitch-angle scattering collision is important.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T09:57:50Z
      DOI: 10.1063/5.0123241
       
  • Ray-based cross-beam energy transfer modeling for broadband lasers

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      Authors: R. K. Follett, A. Colaïtis, A. G. Seaton, H. Wen, D. Turnbull, D. H. Froula, J. P. Palastro
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Broadband lasers have the potential to mitigate cross-beam energy transfer (CBET) in direct-drive inertial confinement fusion (ICF) experiments. A quantitative assessment of the bandwidth required for CBET mitigation necessitates the development of broadband ray-based CBET models that can be implemented in the radiation-hydrodynamic codes that are used to design ICF experiments. Two different approaches to broadband ray-based CBET modeling (discrete and fixed spectrum) are developed and compared to wave-based calculations. Both approaches give good agreement with wave-based calculations in ICF-relevant configurations. Full-scale 3D calculations show that the bandwidth required for adequate CBET mitigation increases with increasing scale and drive intensity.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T09:56:42Z
      DOI: 10.1063/5.0137420
       
  • Effect of electromagnetic wave reflection from conducting surfaces on blob
           dynamics in the tokamak scrape-off layer

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      Authors: A. A. Stepanenko
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      Electromagnetic dynamics of blobs in hot scrape-off-layer plasmas of the tokamak are affected by excitation of the Alfvén waves and their subsequent propagation to the machine first wall along open magnetic field lines. In this study, the interaction of electromagnetic perturbations with the conducting tokamak wall and the resulting impact of these perturbations on the motion of filaments at the tokamak edge are analyzed. The model describing blob dynamics is presented. To describe the reflection of the Alfvén waves from the tokamak wall, the new form of sheath boundary conditions for the parallel current and electrostatic potential at the plasma–sheath interface is proposed. It is demonstrated that depending on the wall resistivity, the waves can be either absorbed or reflected by the wall, influencing the excitation of electromagnetic fluctuations inside the filament plasma. The theoretical conclusions of the study are supported with the BOUT++ numerical modeling of blob dynamics at the edge of the DIII-D and NSTX tokamaks. It is shown that taking the reflective boundary conditions into account leads to the excitation of the standing Alfvén waves in the filament, periodically canceling the electrostatic currents inside the blob.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T09:56:39Z
      DOI: 10.1063/5.0140097
       
  • Preface to Special Topic: Plasma Physics from the Magnetospheric
           Multiscale Mission

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      Authors: Julia E. Stawarz, Kevin J. Genestreti
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      NASA's Magnetospheric Multiscale (MMS) mission is a four-spacecraft formation of Earth orbiting satellites that have been providing unparalleled measurements of the local kinetic-scale plasma dynamics in near-Earth space for the past 8 years. The spacecraft carry a full complement of space plasma instrumentation capable of measuring the 3D electromagnetic fields and particle distribution functions at cadences up to 100 times faster than previous missions and with interspacecraft separations as small as [math] km, approaching the characteristic electron scales in many of the plasmas that MMS samples. In this Special Topic, we bring together 26 papers covering a broad range of topics—from magnetic reconnection, shocks, and turbulence to some of the basic nuances of collisionless dynamics—highlighting the many ways in which MMS is helping us to better understand both the dynamics of Earth's magnetosphere and the fundamental physics of plasmas.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T09:54:11Z
      DOI: 10.1063/5.0148163
       
  • 3D simulation of lower-hybrid drift waves in strong guide field asymmetric
           reconnection in laboratory experiments

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      Authors: J. Ng, J. Yoo, L.-J. Chen, N. Bessho, H. Ji
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The magnetic reconnection experiment has recently seen short wavelength ([math]) lower-hybrid waves near the electron diffusion region in strong guide field reconnection. Based on plasma parameters from the experiment, we perform a three-dimensional fully kinetic simulation in order to investigate the generation of the lower-hybrid waves and their effects on the reconnection process. We find that the low-beta regions around the reconnection site are unstable to the lower-hybrid drift instability propagating in the outflow direction, driven by the difference between the electron and ion outflows. The waves modify the electron distributions, leading to periodic opening and closing of gaps in electron velocity space, and provide a small contribution to the anomalous resistivity. Finally, the simulation results are discussed in the context of space observations and laboratory experiments.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T09:54:09Z
      DOI: 10.1063/5.0138278
       
  • Laser repointing scheme for octahedral spherical hohlraums on the SGIII
           laser facility

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      Authors: Hui Cao, Xufei Xie, Yaohua Chen, Yunsong Dong, Liquan Wang, Zhurong Cao, Xu Chen, Qiangqiang Wang, Wei Zhou, Wei Zhang, Zhichao Li, Sanwei Li, Bo Deng, Liang Hao, Shu Li, Junfeng Wu, Guoli Ren, Xudeng Hang, Wenyi Huo, Xiaoxia Huang, Xiaoshi Peng, Dong Yang, Tao Xu, Lifei Hou, Xingsen Che, Liang Guo, Huabing Du, Xiaoan He, Chaoguang Li, Pin Yang, Qianqian Gu, Yuancheng Wang, Kuixing Zheng, Yunbao Huang, Bin Feng, Guanghui Yuan, Baibin Jiang, Haijun Zhang, Feng Wang, Jiamin Yang, Shenye Liu, Jun Xie, Zhibing He, Kai Du, Jie Liu, Shiyang Zou, Yongkun Ding, Qihua Zhu, Ke Lan
      Abstract: Physics of Plasmas, Volume 30, Issue 4, April 2023.
      The novel octahedral spherical hohlraum can provide an ideal and practical approach for the next generation of laser systems to support both direct and indirect drive to achieve predictable and reproducible fusion gain via multiple schemes. To demonstrate its advantage in a naturally high symmetry at a cylindrically configured laser facility, it requires to repoint the laser beams to approach as close as possible the ideal octahedral beam configuration with an injection angle (the angle between a beam and the normal direction of its laser entrance hole (LEH)) ranging from 50° to 60°. We report our investigation and experiment on the optimum repointing scheme at the SGIII facility, which uses 32 beams, with 8 beams entering each polar LEH at 49.5° and 55°, and 4 beams entering each equatorial LEH at 61.5° and 62.1°. It contains residual imbalance between the polar and equatorial beams, leading to an asymmetry dominated by the spherical harmonic Y20 mode, which can be remarkably reduced by the stronger backscatters of equatorial beams. Our experiment demonstrated the feasibility of the 32-beam optimum repointing scheme and generation of 175 eV under 86 kJ inside a 2.4-mm-radius octahedral hohlraum with 0.7-mm-radius LEHs, which provided a strong support for the later experiment on proof-of-concept of octahedral spherical hohlraum [Lan et al., Phys. Rev. Lett. 127, 245001 (2021)]. 2D simulations on LEH closure agree well with the observations. This work opens a novel way of realization of a quasi-spherical irradiation at a cylindrically configured laser facility without supplementary symmetry control.
      Citation: Physics of Plasmas
      PubDate: 2023-04-03T01:03:49Z
      DOI: 10.1063/5.0133806
       
 
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  Subjects -> EARTH SCIENCES (Total: 771 journals)
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Showing 401 - 371 of 371 Journals sorted alphabetically
PFG : Journal of Photogrammetry, Remote Sensing and Geoinformation Science     Hybrid Journal   (Followers: 5)
Photogrammetrie - Fernerkundung - Geoinformation     Full-text available via subscription  
Physical Geography     Hybrid Journal   (Followers: 8)
Physical Science International Journal     Open Access  
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 15)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Metals and Metallography     Hybrid Journal   (Followers: 18)
Physics of Plasmas     Hybrid Journal   (Followers: 11)
Physics of the Earth and Planetary Interiors     Hybrid Journal   (Followers: 34)
Physics of the Solid State     Hybrid Journal   (Followers: 4)
Physics of Wave Phenomena     Hybrid Journal  
Physics World     Full-text available via subscription   (Followers: 18)
Physik in unserer Zeit     Hybrid Journal   (Followers: 9)
Pirineos     Open Access  
Planet     Open Access   (Followers: 4)
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 10)
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Polar Record     Hybrid Journal   (Followers: 2)
Positioning     Open Access   (Followers: 4)
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Precambrian Research     Hybrid Journal   (Followers: 8)
Preview     Hybrid Journal  
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Proceedings of the Yorkshire Geological Society     Hybrid Journal   (Followers: 2)
Progress in Earth and Planetary Science     Open Access   (Followers: 17)
Pure and Applied Geophysics     Hybrid Journal   (Followers: 13)
Quarterly Journal of Engineering Geology and Hydrogeology     Hybrid Journal   (Followers: 5)
Quaternary     Open Access   (Followers: 2)
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Remote Sensing Letters     Hybrid Journal   (Followers: 48)
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Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 17)
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Results in Geophysical Sciences     Open Access   (Followers: 1)
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Revista de Ciências Exatas Aplicadas e Tecnológicas da Universidade de Passo Fundo : CIATEC-UPF     Open Access  
Revista de Ingenieria Sismica     Open Access  
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Revista Geológica de Chile     Open Access  
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Rocks & Minerals     Hybrid Journal   (Followers: 3)
Russian Geology and Geophysics     Hybrid Journal   (Followers: 2)
Russian Journal of Mathematical Physics     Full-text available via subscription  
Russian Journal of Pacific Geology     Hybrid Journal  
Russian Physics Journal     Hybrid Journal   (Followers: 1)
Science China Earth Sciences     Hybrid Journal   (Followers: 3)
Science News     Hybrid Journal   (Followers: 10)
Science of Remote Sensing     Open Access   (Followers: 7)
Scientific Annals of Stefan cel Mare University of Suceava. Geography Series     Open Access  
Scientific Journal of Earth Science     Open Access  
Scientific Reports     Open Access   (Followers: 82)
Sedimentary Geology     Hybrid Journal   (Followers: 19)
Sedimentology     Hybrid Journal   (Followers: 14)
Seismic Instruments     Hybrid Journal   (Followers: 1)
Seismological Research Letters     Full-text available via subscription   (Followers: 12)
Soil Dynamics and Earthquake Engineering     Hybrid Journal   (Followers: 14)
Soil Security     Open Access   (Followers: 6)
Solid Earth     Open Access   (Followers: 5)
Solid Earth Discussions     Open Access   (Followers: 1)
Solid Earth Sciences     Open Access   (Followers: 1)
South African Journal of Geomatics     Open Access   (Followers: 2)
Standort - Zeitschrift für angewandte Geographie     Hybrid Journal   (Followers: 3)
Stratigraphy and Geological Correlation     Full-text available via subscription   (Followers: 2)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 1)
Studia Geotechnica et Mechanica     Open Access  
Studia Universitatis Babes-Bolyai, Geologia     Open Access  
Survey Review     Hybrid Journal   (Followers: 6)
Surveys in Geophysics     Hybrid Journal   (Followers: 3)
Swiss Journal of Palaeontology     Hybrid Journal   (Followers: 4)
Tectonics     Full-text available via subscription   (Followers: 15)
Tectonophysics     Hybrid Journal   (Followers: 24)
Tellus A     Open Access   (Followers: 20)
Tellus B     Open Access   (Followers: 20)
Terra Latinoamericana     Open Access  
Terra Nova     Hybrid Journal   (Followers: 5)
The Compass : Earth Science Journal of Sigma Gamma Epsilon     Open Access  
The Holocene     Hybrid Journal   (Followers: 16)
The Leading Edge     Hybrid Journal   (Followers: 1)
Transportation Infrastructure Geotechnology     Hybrid Journal   (Followers: 8)
Turkish Journal of Earth Sciences     Open Access  
UD y la Geomática     Open Access  
Unconventional Resources     Open Access  
Underwater Technology: The International Journal of the Society for Underwater     Full-text available via subscription   (Followers: 1)
Universal Journal of Geoscience     Open Access  
Unoesc & Ciência - ACET     Open Access  
Vadose Zone Journal     Open Access   (Followers: 5)
Volcanica     Open Access  
Water     Open Access   (Followers: 11)
Water International     Hybrid Journal   (Followers: 19)
Water Resources     Hybrid Journal   (Followers: 21)
Water Resources Research     Full-text available via subscription   (Followers: 101)
Watershed Ecology and the Environment     Open Access  
Weather, Climate, and Society     Hybrid Journal   (Followers: 14)
Wiley Interdisciplinary Reviews - Climate Change     Hybrid Journal   (Followers: 34)
World Environment     Open Access   (Followers: 1)
Yearbook of the Association of Pacific Coast Geographers     Full-text available via subscription   (Followers: 2)
Yugra State University Bulletin     Open Access   (Followers: 1)
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften     Full-text available via subscription   (Followers: 3)
Zeitschrift für Geomorphologie     Full-text available via subscription   (Followers: 5)
Zitteliana     Open Access   (Followers: 3)
Землеустрій, кадастр і моніторинг земель     Open Access   (Followers: 1)

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