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Barbhuiya MH, Cassak PA, Adhikari S, Parashar TN, Liang H, Argall MR. Higher-order nonequilibrium term: Effective power density quantifying evolution towards or away from local thermodynamic equilibrium. Phys Rev E 2024; 109:015205. [PMID: 38366463 DOI: 10.1103/physreve.109.015205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 12/05/2023] [Indexed: 02/18/2024]
Abstract
A common approach to assess the nature of energy conversion in a classical fluid or plasma is to compare power densities of the various possible energy conversion mechanisms. A leading research area is quantifying energy conversion for systems that are not in local thermodynamic equilibrium (LTE), as is common in a number of fluid and plasma systems. Here we introduce the "higher-order nonequilibrium term" (HORNET) effective power density, which quantifies the rate of change of departure of a phase space density from LTE. It has dimensions of power density, which allows for quantitative comparisons with standard power densities. We employ particle-in-cell simulations to calculate HORNET during two processes, magnetic reconnection and decaying kinetic turbulence in collisionless magnetized plasmas, that inherently produce non-LTE effects. We investigate the spatial variation of HORNET and the time evolution of its spatial average. By comparing HORNET with power densities describing changes to the internal energy (pressure dilatation, Pi-D, and divergence of the vector heat flux density), we find that HORNET can be a significant fraction of these other measures (8% and 35% for electrons and ions, respectively, for reconnection; up to 67% for both electrons and ions for turbulence), meaning evolution of the system towards or away from LTE can be dynamically important. Applications to numerous plasma phenomena are discussed.
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Affiliation(s)
- M Hasan Barbhuiya
- Department of Physics and Astronomy and the Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA
| | - Paul A Cassak
- Department of Physics and Astronomy and the Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA
| | - Subash Adhikari
- Department of Physics and Astronomy and the Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA
| | - Tulasi N Parashar
- School of Chemical and Physical Sciences, Victoria University of Wellington, Gate 7, Kelburn Parade, Wellington 6012, New Zealand
| | - Haoming Liang
- Department of Astronomy, University of Maryland College Park, College Park, Maryland 20742, USA and NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - Matthew R Argall
- Space Science Center, Institute for the Study of Earth, Oceans, and Space and University of New Hampshire, Durham, New Hampshire 03824, USA
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2
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Gong Z, Shen X, Hatsagortsyan KZ, Keitel CH. Electron Slingshot Acceleration in Relativistic Preturbulent Shocks Explored via Emitted Photon Polarization. PHYSICAL REVIEW LETTERS 2023; 131:225101. [PMID: 38101383 DOI: 10.1103/physrevlett.131.225101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/23/2023] [Accepted: 10/23/2023] [Indexed: 12/17/2023]
Abstract
Transient electron dynamics near the interface of counterstreaming plasmas at the onset of a relativistic collisionless shock (RCS) is investigated using particle-in-cell simulations. We identify a slingshotlike injection process induced by the drifting electric field sustained by the flowing focus of backward-moving electrons, which is distinct from the well-known stochastic acceleration. The flowing focus signifies the plasma kinetic transition from a preturbulent laminar motion to a chaotic turbulence. We find a characteristic correlation between the electron dynamics in the slingshot acceleration and the photon emission features. In particular, the integrated radiation from the RCS exhibits a counterintuitive nonmonotonic dependence of the photon polarization degree on the photon energy, which originates from a polarization degradation of relatively high-energy photons emitted by the slingshot-injected electrons. Our results demonstrate the potential of photon polarization as an essential information source in exploring intricate transient dynamics in RCSs with relevance for Earth-based plasma and astrophysical scenarios.
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Affiliation(s)
- Zheng Gong
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Xiaofei Shen
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | | | - Christoph H Keitel
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
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3
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Ly MN, Sano T, Sakawa Y, Sentoku Y. Conditions of structural transition for collisionless electrostatic shock. Phys Rev E 2023; 108:025208. [PMID: 37723746 DOI: 10.1103/physreve.108.025208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 08/01/2023] [Indexed: 09/20/2023]
Abstract
Collisionless shock acceleration, which transfers localized particle energies to nonthermal energetic particles via electromagnetic potential, is ubiquitous in space plasma. We investigate dynamics of collisionless electrostatic shocks that appear at the interface of two plasma slabs with different pressures using one-dimensional particle-in-cell (PIC) simulations and find that the shock structure transforms to a double-layer structure at the high density gradient. The threshold condition of the structure transformation is identified as density ratio of the two plasma slabs Γ ∼40 regardless of the temperature ratio between them. We then update the collisionless shock model that takes into account density expansion effects caused by a rarefaction wave to improve the prediction of the critical Mach numbers. These critical Mach numbers are benchmarked by PIC simulations for a wide range of Γ. Furthermore, we introduce a semianalytical approach to forecast the shock velocity just from the initial conditions based on a concept of the accelerated fraction α.
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Affiliation(s)
- Minh Nhat Ly
- Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Takayoshi Sano
- Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Youichi Sakawa
- Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yasuhiko Sentoku
- Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan
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4
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Gong Z, Hatsagortsyan KZ, Keitel CH. Electron Polarization in Ultrarelativistic Plasma Current Filamentation Instabilities. PHYSICAL REVIEW LETTERS 2023; 130:015101. [PMID: 36669225 DOI: 10.1103/physrevlett.130.015101] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/30/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Plasma current filamentation of an ultrarelativistic electron beam impinging on an overdense plasma is investigated, with emphasis on radiation-induced electron polarization. Particle-in-cell simulations provide the classification and in-depth analysis of three different regimes of the current filaments, namely, the normal filament, abnormal filament, and quenching regimes. We show that electron radiative polarization emerges during the instability along the azimuthal direction in the momentum space, which significantly varies across the regimes. We put forward an intuitive Hamiltonian model to trace the origin of the electron polarization dynamics. In particular, we discern the role of nonlinear transverse motion of plasma filaments, which induces asymmetry in radiative spin flips, yielding an accumulation of electron polarization. Our results break the conventional perception that quasisymmetric fields are inefficient for generating radiative spin-polarized beams, suggesting the potential of electron polarization as a source of new information on laboratory and astrophysical plasma instabilities.
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Affiliation(s)
- Zheng Gong
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | | | - Christoph H Keitel
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
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5
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Particle Acceleration in Mildly Relativistic Outflows of Fast Energetic Transient Sources. UNIVERSE 2022. [DOI: 10.3390/universe8010032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recent discovery of fast blue optical transients (FBOTs)—a new class of energetic transient sources—can shed light on the long-standing problem of supernova—long gamma-ray burst connections. A distinctive feature of such objects is the presence of modestly relativistic outflows which place them in between the non-relativistic and relativistic supernovae-related events. Here we present the results of kinetic particle-in-cell and Monte Carlo simulations of particle acceleration and magnetic field amplification by shocks with the velocities in the interval between 0.1 and 0.7 c. These simulations are needed for the interpretation of the observed broad band radiation of FBOTs. Their fast, mildly to moderately relativistic outflows may efficiently accelerate relativistic particles. With particle-in-cell simulations we demonstrate that synchrotron radiation of accelerated relativistic electrons in the shock downstream may fit the observed radio fluxes. At longer timescales, well beyond those reachable within a particle-in-cell approach, our nonlinear Monte Carlo model predicts that protons and nuclei can be accelerated to petaelectronvolt (PeV) energies. Therefore, such fast and energetic transient sources can contribute to galactic populations of high energy cosmic rays.
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Lemoine M, Vanthieghem A, Pelletier G, Gremillet L. Physics of relativistic collisionless shocks. II. Dynamics of the background plasma. Phys Rev E 2019; 100:033209. [PMID: 31639946 DOI: 10.1103/physreve.100.033209] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Indexed: 11/07/2022]
Abstract
In this second paper of a series, we discuss the dynamics of a plasma entering the precursor of an unmagnetized, relativistic collisionless pair shock. We discuss how this background plasma is decelerated and heated through its interaction with a microturbulence that results from the growth of a current filamentation instability in the shock precursor. We make use, in particular, of the reference frame R_{w} in which the turbulence is mostly magnetic. This frame moves at relativistic velocities towards the shock front at rest, decelerating gradually from the far to the near precursor. In a first part, we construct a fluid model to derive the deceleration law of the background plasma expected from the scattering of suprathermal particles off the microturbulence. This law leads to the relationship γ_{p}∼ξ_{b}^{-1/2} between the background plasma Lorentz factor γ_{p} and the normalized pressure of the beam ξ_{b}; it is found to match nicely the spatial profiles observed in large-scale 2D3V particle-in-cell simulations. In a second part, we model the dynamics of the background plasma at the kinetic level, incorporating the inertial effects associated with the deceleration of R_{w} into a Vlasov-Fokker-Planck equation for pitch-angle diffusion. We show how the effective gravity in R_{w} drives the background plasma particles through friction on the microturbulence, leading to efficient plasma heating. Finally, we compare a Monte Carlo simulation of our model with dedicated PIC simulations and conclude that it can satisfactorily reproduce both the heating and the deceleration of the background plasma in the shock precursor, thereby providing a successful one-dimensional description of the shock transition at the microscopic level.
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Affiliation(s)
- Martin Lemoine
- Institut d'Astrophysique de Paris, CNRS - Sorbonne Université, 98 bis boulevard Arago, F-75014 Paris, France
| | - Arno Vanthieghem
- Institut d'Astrophysique de Paris, CNRS - Sorbonne Université, 98 bis boulevard Arago, F-75014 Paris, France.,Sorbonne Université, Institut Lagrange de Paris (ILP), 98 bis bvd Arago, F-75014 Paris, France
| | - Guy Pelletier
- UJF-Grenoble, CNRS-INSU, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), F-38041 Grenoble, France
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7
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Lemoine M, Gremillet L, Pelletier G, Vanthieghem A. Physics of Weibel-Mediated Relativistic Collisionless Shocks. PHYSICAL REVIEW LETTERS 2019; 123:035101. [PMID: 31386457 DOI: 10.1103/physrevlett.123.035101] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/20/2019] [Indexed: 06/10/2023]
Abstract
We develop a comprehensive theoretical model of relativistic collisionless pair shocks mediated by the current filamentation instability. We notably characterize the noninertial frame in which this instability is of a mostly magnetic nature, and describe at a microscopic level the deceleration and heating of the incoming background plasma through its collisionless interaction with the electromagnetic turbulence. Our model compares well to large-scale 2D3V particle-in-cell simulations, and provides an important touchstone for the phenomenology of such plasma systems.
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Affiliation(s)
- Martin Lemoine
- Institut d'Astrophysique de Paris, CNRS-Sorbonne Université, 98 bis boulevard Arago, F-75014 Paris, France
| | | | - Guy Pelletier
- Université Grenoble Alpes, CNRS-INSU, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), F-38041 Grenoble, France
| | - Arno Vanthieghem
- Institut d'Astrophysique de Paris, CNRS-Sorbonne Université, 98 bis boulevard Arago, F-75014 Paris, France
- Sorbonne Universités, Institut Lagrange de Paris (ILP), 98 bis boulevard Arago, F-75014 Paris, France
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8
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Acceleration of Cosmic Rays in Supernova Shocks: Elemental Selectivity of the Injection Mechanism. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/1538-4357/aafdae] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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9
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Palmroth M, Ganse U, Pfau-Kempf Y, Battarbee M, Turc L, Brito T, Grandin M, Hoilijoki S, Sandroos A, von Alfthan S. Vlasov methods in space physics and astrophysics. ACTA ACUST UNITED AC 2018; 4:1. [PMID: 30680308 PMCID: PMC6319499 DOI: 10.1007/s41115-018-0003-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/06/2018] [Indexed: 11/26/2022]
Abstract
This paper reviews Vlasov-based numerical methods used to model plasma in space physics and astrophysics. Plasma consists of collectively behaving charged particles that form the major part of baryonic matter in the Universe. Many concepts ranging from our own planetary environment to the Solar system and beyond can be understood in terms of kinetic plasma physics, represented by the Vlasov equation. We introduce the physical basis for the Vlasov system, and then outline the associated numerical methods that are typically used. A particular application of the Vlasov system is Vlasiator, the world’s first global hybrid-Vlasov simulation for the Earth’s magnetic domain, the magnetosphere. We introduce the design strategies for Vlasiator and outline its numerical concepts ranging from solvers to coupling schemes. We review Vlasiator’s parallelisation methods and introduce the used high-performance computing (HPC) techniques. A short review of verification, validation and physical results is included. The purpose of the paper is to present the Vlasov system and introduce an example implementation, and to illustrate that even with massive computational challenges, an accurate description of physics can be rewarding in itself and significantly advance our understanding. Upcoming supercomputing resources are making similar efforts feasible in other fields as well, making our design options relevant for others facing similar challenges.
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Affiliation(s)
- Minna Palmroth
- Department of Physics, University of Helsinki, Helsinki, Finland
- Finnish Meteorological Institute, Helsinki, Finland
| | - Urs Ganse
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Yann Pfau-Kempf
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Markus Battarbee
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Lucile Turc
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Thiago Brito
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Maxime Grandin
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Sanni Hoilijoki
- Laboratory for Atmospheric and Space Plasma Physics, University of Colorado at Boulder, Boulder, CO USA
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10
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11
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Practical Aspects of X-ray Imaging Polarimetry of Supernova Remnants and Other Extended Sources. GALAXIES 2018. [DOI: 10.3390/galaxies6020046] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Kai Y, Garen W, Teubner U. Experimental Investigations on Microshock Waves and Contact Surfaces. PHYSICAL REVIEW LETTERS 2018; 120:064501. [PMID: 29481242 DOI: 10.1103/physrevlett.120.064501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Indexed: 06/08/2023]
Abstract
The present work reports on progress in the research of a microshock wave. Because of the lack of a good understanding of the propagation mechanism of the microshock flow system (shock wave, contact surface, and boundary layer), the current work concentrates on measuring microshock flows with special attention paid to the contact surface. A novel setup involving a glass capillary (with a 200 or 300 μm hydraulic diameter D) and a high-speed magnetic valve is applied to generate a shock wave with a maximum initial Mach number of 1.3. The current work applies a laser differential interferometer to perform noncontact measurements of the microshock flow's trajectory, velocity, and density. The current work presents microscale measurements of the shock-contact distance L that solves the problem of calculating the scaling factor Sc=Re×D/(4L) (introduced by Brouillette), which is a parameter characterizing the scaling effects of shock waves. The results show that in contrast to macroscopic shock waves, shock waves at the microscale have a different propagation or attenuation mechanism (key issue of this Letter) which cannot be described by the conventional "leaky piston" model. The main attenuation mechanism of microshock flow may be the ever slower moving contact surface, which drives the shock wave. Different from other measurements using pressure transducers, the current setup for density measurements resolves the whole microshock flow system.
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Affiliation(s)
- Yun Kai
- Hochschule Emden/Leer, University of Applied Sciences, Institute for Laser and Optics, Constantiaplatz 4, 26723 Emden, Germany
- Carl von Ossietzky University of Oldenburg, Institute of Physics, 26111 Oldenburg, Germany
| | - Walter Garen
- Hochschule Emden/Leer, University of Applied Sciences, Institute for Laser and Optics, Constantiaplatz 4, 26723 Emden, Germany
| | - Ulrich Teubner
- Hochschule Emden/Leer, University of Applied Sciences, Institute for Laser and Optics, Constantiaplatz 4, 26723 Emden, Germany
- Carl von Ossietzky University of Oldenburg, Institute of Physics, 26111 Oldenburg, Germany
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13
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Ross JS, Higginson DP, Ryutov D, Fiuza F, Hatarik R, Huntington CM, Kalantar DH, Link A, Pollock BB, Remington BA, Rinderknecht HG, Swadling GF, Turnbull DP, Weber S, Wilks S, Froula DH, Rosenberg MJ, Morita T, Sakawa Y, Takabe H, Drake RP, Kuranz C, Gregori G, Meinecke J, Levy MC, Koenig M, Spitkovsky A, Petrasso RD, Li CK, Sio H, Lahmann B, Zylstra AB, Park HS. Transition from Collisional to Collisionless Regimes in Interpenetrating Plasma Flows on the National Ignition Facility. PHYSICAL REVIEW LETTERS 2017; 118:185003. [PMID: 28524679 DOI: 10.1103/physrevlett.118.185003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Indexed: 06/07/2023]
Abstract
A study of the transition from collisional to collisionless plasma flows has been carried out at the National Ignition Facility using high Mach number (M>4) counterstreaming plasmas. In these experiments, CD-CD and CD-CH planar foils separated by 6-10 mm are irradiated with laser energies of 250 kJ per foil, generating ∼1000 km/s plasma flows. Varying the foil separation distance scales the ion density and average bulk velocity and, therefore, the ion-ion Coulomb mean free path, at the interaction region at the midplane. The characteristics of the flow interaction have been inferred from the neutrons and protons generated by deuteron-deuteron interactions and by x-ray emission from the hot, interpenetrating, and interacting plasmas. A localized burst of neutrons and bright x-ray emission near the midpoint of the counterstreaming flows was observed, suggesting strong heating and the initial stages of shock formation. As the separation of the CD-CH foils increases we observe enhanced neutron production compared to particle-in-cell simulations that include Coulomb collisions, but do not include collective collisionless plasma instabilities. The observed plasma heating and enhanced neutron production is consistent with the initial stages of collisionless shock formation, mediated by the Weibel filamentation instability.
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Affiliation(s)
- J S Ross
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - D P Higginson
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - D Ryutov
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - F Fiuza
- SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94305, USA
| | - R Hatarik
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - C M Huntington
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - D H Kalantar
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - A Link
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - B B Pollock
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - B A Remington
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - H G Rinderknecht
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - G F Swadling
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - D P Turnbull
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - S Weber
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - S Wilks
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - D H Froula
- Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14623, USA
| | - M J Rosenberg
- Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14623, USA
| | - T Morita
- Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580, Japan
| | - Y Sakawa
- Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - H Takabe
- Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - R P Drake
- University of Michigan, Ann Arbor, Michigan 48109, USA
| | - C Kuranz
- University of Michigan, Ann Arbor, Michigan 48109, USA
| | - G Gregori
- Department of Physics, University of Oxford, Parks Road OX1 3PU, United Kingdom
| | - J Meinecke
- Department of Physics, University of Oxford, Parks Road OX1 3PU, United Kingdom
| | - M C Levy
- Department of Physics, University of Oxford, Parks Road OX1 3PU, United Kingdom
| | - M Koenig
- LULI, Ecole Polytechnique, CNRS, Universit Paris 6, 91128 Palaiseau, France
| | - A Spitkovsky
- Princeton University, Princeton, New Jersey 08544, USA
| | - R D Petrasso
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - C K Li
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - H Sio
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - B Lahmann
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A B Zylstra
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - H-S Park
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
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14
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Gueroult R, Ohsawa Y, Fisch NJ. Role of Magnetosonic Solitons in Perpendicular Collisionless Shock Reformation. PHYSICAL REVIEW LETTERS 2017; 118:125101. [PMID: 28388176 DOI: 10.1103/physrevlett.118.125101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Indexed: 06/07/2023]
Abstract
The nature of the magnetic structure arising from ion specular reflection in shock compression studies is examined by means of 1D particle-in-cell simulations. Propagation speed, field profiles, and supporting currents for this magnetic structure are shown to be consistent with a magnetosonic soliton. Coincidentally, this structure and its evolution are typical of foot structures observed in perpendicular shock reformation. To reconcile these two observations, we propose, for the first time, that shock reformation can be explained as the result of the formation, growth, and subsequent transition to a supercritical shock of a magnetosonic soliton. This argument is further supported by the remarkable agreement found between the period of the soliton evolution cycle and classical reformation results. This new result suggests that the unique properties of solitons can be used to shed new light on the long-standing issue of shock nonstationarity and its role on particle acceleration.
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Affiliation(s)
- Renaud Gueroult
- Laplace, Université de Toulouse, CNRS, INPT, UPS, 31062 Toulouse, France
| | - Yukiharu Ohsawa
- Department of Physics, Nagoya University, Nagoya 464-8602, Japan
| | - Nathaniel J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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15
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Bykov AM, Ellison DC, Osipov SM. Nonlinear Monte Carlo model of superdiffusive shock acceleration with magnetic field amplification. Phys Rev E 2017; 95:033207. [PMID: 28415375 DOI: 10.1103/physreve.95.033207] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Indexed: 11/07/2022]
Abstract
Fast collisionless shocks in cosmic plasmas convert their kinetic energy flow into the hot downstream thermal plasma with a substantial fraction of energy going into a broad spectrum of superthermal charged particles and magnetic fluctuations. The superthermal particles can penetrate into the shock upstream region producing an extended shock precursor. The cold upstream plasma flow is decelerated by the force provided by the superthermal particle pressure gradient. In high Mach number collisionless shocks, efficient particle acceleration is likely coupled with turbulent magnetic field amplification (MFA) generated by the anisotropic distribution of accelerated particles. This anisotropy is determined by fast particle transport, making the problem strongly nonlinear and multiscale. Here, we present a nonlinear Monte Carlo model of collisionless shock structure with superdiffusive propagation of high-energy Fermi accelerated particles coupled to particle acceleration and MFA, which affords a consistent description of strong shocks. A distinctive feature of the Monte Carlo technique is that it includes the full angular anisotropy of the particle distribution at all precursor positions. The model reveals that the superdiffusive transport of energetic particles (i.e., Lévy-walk propagation) generates a strong quadruple anisotropy in the precursor particle distribution. The resultant pressure anisotropy of the high-energy particles produces a nonresonant mirror-type instability that amplifies compressible wave modes with wavelengths longer than the gyroradii of the highest-energy protons produced by the shock.
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Affiliation(s)
- Andrei M Bykov
- Ioffe Institute, St. Petersburg State Polytechnical University, St. Petersburg 194021, Russia and International Space Science Institute, Bern, Switzerland
| | - Donald C Ellison
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
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