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In collisional fluids, a number of key processes rely on the frequency of binary collisions. Collisions seem necessary to generate a shock wave when two fluids collide fast enough, to fulfill the Rankine-Hugoniot relations, to establish an…

Plasma Physics · Physics 2019-02-20 Antoine Bret

Plasma shock waves widely exist and play an important role in high-energy-density environment, especially in the inertial confinement fusion. Due to the large gradient of macroscopic physical quantities and the coupled thermal, electrical,…

Plasma Physics · Physics 2023-08-25 Zhipeng Liu , Jiahui Song , Aiguo Xu , Yudong Zhang , Kan Xie

We model relativistically colliding plasma by PIC simulations in one and two spatial dimensions, taking an ion-to-electron mass ratio of 400. Energy dissipation by a wave precursor of mixed polarity and different densities of the colliding…

Astrophysics · Physics 2009-11-13 M. E. Dieckmann , P. K. Shukla , L. O. C. Drury

Magnetized collisionless shocks drive particle acceleration broadly in space and astrophysics. We perform the first large-scale particle-in-cell simulations with realistic laboratory parameters (density, temperature, and velocity) to…

Plasma Physics · Physics 2024-05-24 P. Liu , D. Wu , D. W. Yuan , G. Zhao , Z. M. Sheng , X. T. He , J. Zhang

We study the interaction of upstream ultra-low frequency (ULF) waves with collisionless shocks by analyzing the outputs of eleven 2D local hybrid simulation runs. Our simulated shocks have Alfv\'enic Mach numbers between 4.29-7.42 and their…

The properties of collisionless shocks, like the density jump, are usually derived from magnetohydrodynamics (MHD), where isotropic pressures are assumed. Yet, in a collisionless plasma, an external magnetic field can sustain a stable…

Plasma Physics · Physics 2022-07-20 Antoine Bret , Ramesh Narayan

Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of non-thermal particles and high-energy radiation. In the absence of particle collisions in the system, theoretical works show that the…

We perform direct numerical simulations of shock-wave/boundary-layer interactions (SBLI) at Mach number M = 1.7 to investigate the influence of the state of the incoming boundary layer on the interaction properties. We reproduce and extend…

Fluid Dynamics · Physics 2017-09-18 Russell Quadros , Matteo Bernardini

Energetic electromagnetic emissions by astrophysical jets like those that are launched during the collapse of a massive star and trigger gamma-ray bursts (GRBs) are partially attributed to relativistic internal shocks. The shocks are…

High Energy Astrophysical Phenomena · Physics 2017-09-12 M E Dieckmann , A Bret

To expand on recent work, we introduce collisional terms in the analysis of the warm ion-electron, two-fluid equations for a homogeneous plasma at rest. Consequently, the plasma is now described by six variables: the magnetisation, the…

Plasma Physics · Physics 2024-05-21 Joeri De Vadder , Jordi De Jonghe , Rony Keppens

Relativistic collisionless shocks in electron-ion plasma are thought to occur in the afterglow phase of Gamma-Ray Bursts (GRBs), and in other environments where relativistic flows interact with the interstellar medium. A particular regime…

Astrophysics · Physics 2009-11-13 Anatoly Spitkovsky

A simplified model of particle transport at a quasiparallel one-dimensional collisionless shock is suggested. In this model the MHD-turbulence behind the shock is dominated by a circularly polarized, large amplitude Alfv\'en wave originated…

Astrophysics · Physics 2008-11-26 M. A. Malkov

The results of hybrid simulation of low-beta supercritical quasi-parallel shocks in high metallicity plasma are presented. The structure of upstream and downstream turbulence is addressed and velocities of the corresponding scattering…

High Energy Astrophysical Phenomena · Physics 2020-01-08 J. A. Kropotina , K. P. Levenfish , A. M. Bykov

Laser-driven collisonless electrostatic shock formation and the subsequent ion acceleration have been studied in near critical density plasmas. Particle-in-cell simulations show that both the speed of laser-driven collisionless…

Plasma Physics · Physics 2016-11-22 M. Liu , S. M. Weng , Y. T. Li , D. W. Yuan , M. Chen , P. Mulser , Z. M. Sheng , M. Murakami , L. L. Yu , X. L. Zheng , J. Zhang

The kinetic theory of collisionless electrostatic shocks resulting from the collision of plasma slabs with different temperatures and densities is presented. The theoretical results are confirmed by self-consistent particle-in-cell…

Plasma Physics · Physics 2009-11-11 G. Sorasio , M. Marti , R. Fonseca , L. O. Silva

Within the context of Magnetohydrodynamics (MHD), the properties of a parallel shock do not depend on the field strength, as the field and the fluid are disconnected for such a geometry. However, in the collisionless case, the field can…

Plasma Physics · Physics 2021-08-25 Antoine Bret

Collisionless shocks are pervasive in astrophysics and they are critical to understand cosmic ray acceleration. Laboratory experiments with intense lasers are now opening the way to explore and characterise the underlying microphysics,…

Plasma Physics · Physics 2014-01-14 A. Stockem , F. Fiuza , A. Bret , R. A. Fonseca , L. O. Silva

We study a relativistic collisionless electron-positron shock propagating into an unmagnetized ambient medium using 2D particle-in-cell simulations of unprecedented duration and size. The shock generates intermittent magnetic structures of…

High Energy Astrophysical Phenomena · Physics 2024-03-12 Daniel Groselj , Lorenzo Sironi , Anatoly Spitkovsky

Transport properties of high-energy-density plasmas are influenced by the ion collision rate. Traditionally, this rate involves the Coulomb logarithm, $\ln\Lambda$. Typical values of $\ln\Lambda$ are $\approx 10~\mbox{to}~20$ in kinetic…

Shocks act to convert incoming supersonic flows to heat, and in collisionless plasmas the shock layer forms on kinetic plasma scales through collective electromagnetic effects. These collisionless shocks have been observed in many space and…