JournalTOCs

Plasma Physics and Controlled Fusion
Journal Prestige (SJR): 0.69

Citation Impact (citeScore): 2
Number of Followers: 9

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0741-3335 - ISSN (Online) 1361-6587
Published by IOP

[40 journals]

The role of field correlations on turbulent dissipation
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  Authors: Annick Pouquet
  First page: 033002
  Abstract: Nonlinear phenomena and turbulence are central to our understanding and modeling of the dynamics of fluids and plasmas, and yet they still resist analytical resolution in many instances. However, progress has been made recently, displaying a richness of phenomena, which was somewhat unexpected a few years back, such as double constant-flux cascades of the same invariant for both large and small scales, or the presence of non-Gaussian wings in large-scale fields, for fluids and plasmas. Here, I will concentrate on the direct measurement of the magnitude of dissipation and the evaluation of intermittency in a turbulent plasma using exact laws stemming from invariance principles and involving cross-correlation tensors with both the velocity and the magnetic fields. I will illustrate these points through scaling laws, together with data analysis from existing experiments, observations and numerical simulations. Finally, I will also briefly explore the possible implications for the validity and use of several modeling strategies.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-01T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Plasma heating and particle acceleration in collisionless shocks through
astrophysical observations
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  Authors: M Miceli
  First page: 034003
  Abstract: Supernova remnants (SNRs), the products of stellar explosions, are powerful astrophysical laboratories, which allow us to study the physics of collisionless shocks, thanks to their bright electromagnetic emission. Blast wave shocks generated by supernovae (SNe) provide us with an observational window to study extreme conditions, characterized by high Mach (and Alfvénic Mach) numbers, together with powerful nonthermal processes. In collisionless shocks, temperature equilibration between different species may not be reached at the shock front. In this framework, different particle species may be heated at different temperatures (depending on their mass) in the post-shock medium of SNRs. SNRs are also characterized by broadband nonthermal emission stemming from the shock front as a result of nonthermal populations of leptons and hadrons. These particles, known as cosmic rays, are accelerated up to ultrarelativistic energies via diffusive shock acceleration. If SNRs lose a significant fraction of their ram energy to accelerate cosmic rays, the shock dynamics should be altered with respect to the adiabatic case. This shock modification should result in an increase in the total shock compression ratio with respect to the Rankine–Hugoniot value of 4. Here, I show that the combination of x-ray high resolution spectroscopy (to measure ion temperatures) and moderate resolution spectroscopy (for a detailed diagnostic of the post-shock density) can be exploited to study both the heating mechanism and the particle acceleration in collisionless shocks. I report on new results on the temperatures measured for different ion species in the remnant of the SN observed in 1987 in the Large Magellanic Cloud (SN 1987A). I also discuss evidence of shock modification recently obtained in the remnant of SN 1006 a. D., where the shock compression ratio increases significantly as the angle between the shock velocity and the ambient magnetic field is reduced.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-01T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Full f and δf gyrokinetic particle simulations of Alfvén waves and
energetic particle physics
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  Authors: Zhixin Lu; Guo Meng, Roman Hatzky, Matthias Hoelzl Philipp Lauber
  First page: 034004
  Abstract: In this work, we focus on the development of the particle-in-cell scheme and its application to the studies of Alfvén waves and energetic particle (EP) physics in tokamak plasmas. The and full f schemes are formulated on the same footing adopting mixed variables and the pullback scheme for electromagnetic problems. The TRIMEG-GKX code (Lu et al 2021 J. Comput. Phys. 440 110384) has been upgraded using cubic spline finite elements and full f and schemes. The toroidal Alfvén eigenmode (TAE) driven by EPs has been simulated for the International Tokamak Physics activity (ITPA)-TAE case featured by a small electron skin depth , which is a challenging parameter regime for electromagnetic simulations, especially for the full f model. The simulation results using the scheme are in good agreement with previous work. Excellent performance of the mixed variable/pullback scheme has been observed for both full f and schemes. Simulations with mixed full f EPs and electrons and thermal ions demonstrate the good features of this novel scheme in mitigating the noise level. The full f scheme is a natural choice for EP physics studies, which allows for large variations of EP profiles and distributions in velocity space, providing a powerful tool for kinetic studies using realistic experimental distributions related to intermittent and transient plasma activities.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-01T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Electron and ion acceleration from femtosecond laser-plasma peeler scheme
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  Authors: X F Shen; A Pukhov B Qiao
  First page: 034005
  Abstract: Using three-dimensional particle-in-cell simulations, we further investigate the electron and ion acceleration from femtosecond laser–plasma peeler scheme which was proposed in our recent paper (Shen et al 2021 Phys. Rev. X 11 041002). In addition to the standard setup where a laser pulse impinges on an edge of a single tape target, two new variants of the target, i.e. a parallel tape and a cross tape target, were proposed, where strong surface plasma waves can also be efficiently excited at the front edges of the target. By using a tabletop 200 TW-class laser pulse, we observe generation of high-flux, well-collimated, superponderomotive electrons. More importantly, quasimonoenergetic proton beams can always be obtained in all the three setups, while with the single tape case, the obtained proton beam has the highest peak energy and narrowest spectrum.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-01T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Enhanced polarized proton acceleration driven by femtosecond laser pulses
irradiating a micro-structured solid–gas target
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  Authors: Xue Yan; Yitong Wu, Xuesong Geng, Hui Zhang, Baifei Shen Liangliang Ji
  First page: 035005
  Abstract: Herein, we propose a scheme based on collision-less shock acceleration (CSA) involving the use of composite targets comprising a micro-structured foil and a pre-polarized gas for obtaining high-energy polarized proton beams. Femtosecond laser pulses irradiate a microwire-array (MWA) target and efficiently heat the dense plasma, which moves toward the dilute plasma. Shocks are then introduced in the pre-polarized gas to accelerate upstream spin-polarized protons to relativistic velocities. Based on particle-in-cell simulations with added spin dynamics, protons with energies of 30–300 MeV are produced, and the polarization rate of protons in the high-energy region exceeds 90%. The simulations demonstrate an evident increase in the temperature and number of hot electrons owing to the presence of MWA structures, which increase both the longitudinal electric field strength associated with the shock and the energy of the reflected protons. During CSA, the bipolar magnetic field driven by hot-electron currents demonstrates a weak effect on the polarization level of the accelerated protons, resulting in a high polarization rate. The relationship between the energy of the polarized proton beam and the hot-electron temperature enables an optimization of the micro-structured target and other target components to enhance proton quality via the CSA process.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-01T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Localized absorption of laser energy in X-mode configuration of magnetized
plasma
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  Authors: Ayushi Vashistha; Devshree Mandal, Srimanta Maity Amita Das
  First page: 035006
  Abstract: The heating of ions via lower hybrid (LH) waves has been observed in several astrophysical as well as laboratory plasmas. We have conducted particle-in-cell simulations to demonstrate absorption of the incident laser pulse at a chosen localized point in the plasma target by manipulating its density profile. We show that a part of the incident laser propagates inside the plasma target when its frequency lies below the LH resonance frequency. Thereafter, as it experiences a negative density gradient, it approaches the resonance point where its group velocity approaches zero. This is where the electromagnetic (EM) energy prominently gets converted into the electrostatic and eventually the kinetic energy of ions. Thus, by tailoring the plasma density profile one can have the absorption of incident EM wave energy at a designated location inside the plasma. This may be important in various applications where energy deposition/heating of plasma in a localized region is desirable.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-01T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Reduced transport models for a tokamak flight simulator
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  Authors: M Muraca; E Fable, C Angioni, T Luda, P David, H Zohm, A Di Siena the ASDEX Upgrade Team
  First page: 035007
  Abstract: In this work, a very fast integrated transport model involving every region that interacts directly with the plasma of a tokamak, has been developed. The confined region is modeled in 1.5D, while the scrape-off layer has a 0D structure. For the core region, a physics-based analytical regression based on a set of simulations with the transport model TGLF [Staebler 2005 Phys. Plasmas 12 102508] has been produced. For the H-mode regime, an average edge-localized-modes model is applied in the pedestal region. In the scrape-off layer a two-point model for electron temperature (exhaust) and a particle balance for the species density at the separatrix have been implemented. All the models have first been validated individually in a standalone setting. Finally, six fully integrated simulations of an L-mode discharge, and five H-mode discharges, have been performed in the Fenix flight simulator [Janky et al 2019 Fusion Eng. Des. 146 1926, Fable et al 2022 Plasma Phys. Control. Fusion 64 044002], including transients, matching the experimental trajectories of an ASDEX upgrade discharge during flat-top and ramp-down. A broader validation including more discharges and the ramp-up phase is planned for the near future.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-02T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Drift kinetic effects on plasma response to resonant magnetic perturbation
for EU DEMO design
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  Authors: Lina Zhou; Yueqiang Liu, Hanqing Hu, Mattia Siccinio, Maviglia Francesco, Hartmut Zohm, Leonardo Pigatto, Yong Wang, Li Li, Guangzhou Hao, Xu Yang, Hanyu Zhang, Ping Duan Long Chen
  First page: 035008
  Abstract: A systematic investigation of the plasma response to an externally applied resonant magnetic perturbation (RMP) field, for the purpose of controlling edge localized modes, is carried out for an EU DEMO reference plasma. Particular emphasis is placed on the role of kinetic effects associated with both thermal particles and fusion-born alphas. The single fluid, resistive model predicts a large peak amplification of the n= 1 (n is the toroidal mode number) plasma response to the target equilibrium, which is found to be close to the Troyon no-wall limit. A more advanced response model, including kinetic resonances between the RMP perturbation and drift motions of thermal and energetic particles, on the other hand, finds a strong suppression of the n= 1 field amplification. A major role is played by the precessional drift resonance of fusion-born alphas. A strong parallel sound wave damping model is found to well reproduce the full kinetic response results for the DEMO plasma, in terms of both the resonant field response amplitude and the plasma displacement. Finally, both fluid and kinetic models produce similar responses for the n = 2 and 3 RMP fields for the considered DEMO plasma, whilst kinetic effects again become important for the n = 4 RMP due to proximity of the reference plasma to the no-wall limit for the n = 4 ideal kink instability.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-02T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Reliable measurements of low-density plasmas using a novel Langmuir probe
with a guard tube
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  Authors: Jian-Quan Li; Xin-Yao Xie, Qing-He Zhang Zan-Yang Xing
  First page: 035009
  Abstract: A novel cylindrical Langmuir probe with an optimized probe structure and an additional guard tube is developed to obtain exact plasma electron densities. Using both this novel Langmuir probe and a conventional cylindrical Langmuir probe, a comparative measurement of low-density hot-filament discharge plasmas is performed. Although the plasma potentials and electron temperatures determined by the two probes are almost identical, the electron densities obtained using the conventional Langmuir probe are grossly underestimated by more than 10% compared to those from the novel Langmuir probe. The experimental results demonstrate that optimization of the structure of such cylindrical probes is very important, especially for reliable measurements of low-density plasmas using the Langmuir probe.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-02T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)
Numerical analysis of divertor target heat load of I-modes in comparison
with H-modes of EAST
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  Authors: Min Wang; Xiaogang Wang, Zixi Liu, Xiaoyi Yang, Tianchun Zhou, Hang Si Chao Shen
  First page: 035010
  Abstract: Due to substantial edge transport of particles, I-mode operations offer a high potential for divertor heat load mitigation. In this work, the divertor parameters of I-mode operations on EAST have been investigated using the SOLPS-ITER code, and comparison with H-mode operations has also been made by modeling the I- and H-mode operation processes on EAST. The simulation shows that, for the same separatrix electron density at the outer midplane (OMP) , the upstream electron density of the I-mode is higher than that of the H-mode with no density pedestal, while the upstream temperature of the I-mode is almost the same as that of the H-mode with a temperature pedestal similar to that of the H-mode. As a combined result, the temperature and energy flux peaks of the I-mode are thus lower than those of the H-mode at the divertor target. Further parameter scanning investigation reveals that, under low-density conditions (), the peak energy flow at the target is reduced by ∼34.1%, in the case of the I-mode as compared to the H-mode, while the peak target temperature is dropped by ∼54.6%. Under high-density conditions (), on the other hand, the energy flux and temperature peaks are weakened by ∼28% and ∼30.1%, respectively. The upstream density at detachment onset of an I-mode is also lower than that of an H-mode, by 18.5%. These results suggest that I-mode operation is more appropriate for divertor heat load mitigation than H-mode operation.
  Citation: Plasma Physics and Controlled Fusion
  PubDate: 2023-02-02T00:00:00Z
  Issue No: Vol. 65, No. 3 (2023)