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Rectification and diffusion of non-interacting self-propelled particles is numerically investigated in a two-dimensional corrugated channel. From numerical simulations, we obtain the average velocity and the effective diffusion coefficient.…

Statistical Mechanics · Physics 2014-07-29 Bao-quan Ai , Qiu-yan Chen , Ya-feng He , Feng-guo Li , Wei-rong Zhong

Diffusion of particles in velocity space undergoing turbulent field was extensively studied in the problem of warm beam relaxation. Under low field intensities the diffusion is described by the Fokker-Planck equation with the diffusion…

Plasma Physics · Physics 2007-05-23 Anatoly Zagorodny , Volodymyr Zasenko , Jan Weiland

Diffusive Shock Acceleration (DSA) cannot efficiently accelerate particles without the presence of self-consistently generated or pre-existing strong turbulence ($ \delta B/B \sim 1 $) in the vicinity of the shock. The problem we address in…

High Energy Astrophysical Phenomena · Physics 2018-05-23 Christian Garrel , Loukas Vlahos , Heinz Isliker , Theophilos Pisokas

We study diffusive shock acceleration (DSA) of protons and electrons at nonrelativistic, high Mach number, quasiparallel, collisionless shocks by means of self-consistent 1D particle-in-cell simulations. For the first time, both species are…

High Energy Astrophysical Phenomena · Physics 2015-03-02 Jaehong Park , Damiano Caprioli , Anatoly Spitkovsky

The effect of particles that undergo strong diffusive-shock-acceleration on the stability of the accelerating shock is investigated. A two-fluid model is employed in which the accelerated particles are treated as a fluid whose effect is…

Astrophysics · Physics 2007-05-23 M. Mond , L. O'C. Drury

Collisionless relativistic shocks have been the focus of intense theoretical and numerical investigations in recent years. The acceleration of particles, the generation of electromagnetic microturbulence and the building up of a shock front…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Illya Plotnikov , Guy Pelletier , Martin Lemoine

Theoretical studies of cosmic ray particle acceleration in the first-order Fermi process at relativistic shocks are reviewed. At the beginning we discuss the acceleration processes acting at mildly relativistic shock waves. An essential…

Astrophysics · Physics 2007-05-23 Michal Ostrowski

Relativistic collisionless shocks are associated with efficient particle acceleration when propagating into weakly magnetized homogeneous media; as the magnetization increases, particle acceleration becomes suppressed. We demonstrate that…

High Energy Astrophysical Phenomena · Physics 2023-04-26 Camilia Demidem , Joonas Nättilä , Alexandra Veledina

We analyze the main features of radiation-mediated shocks at arbitrary shock velocities, both non-relativistic and relativistic. We describe two mechanisms, which may lead to formation of a sharp viscous subshock within otherwise smooth…

High Energy Astrophysical Phenomena · Physics 2018-12-27 Evgeny Derishev

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 supernova paradigm for the origin of galactic cosmic rays has been deeply affected by the development of the non-linear theory of particle acceleration at shock waves. Here we discuss the implications of applying such theory to the…

High Energy Astrophysical Phenomena · Physics 2015-03-13 D. Caprioli , E. Amato , P. Blasi

Radio, X-ray, and gamma-ray observations provide us with strong evidence of particle acceleration to multi-TeV energies in various astrophysical sources. Diffusive shock acceleration is one of the most successful models explaining the…

Astrophysics · Physics 2009-11-13 G. Vannoni , S. Gabici , F. A. Aharonian

In this paper, we study shock structures of collisionless shocks in partially ionized plasmas by means of two-dimensional hybrid simulations, where the shock is a perpendicular shock with shock velocity Vsh ~ 40 Va ~ 1333 km/s and the…

High Energy Astrophysical Phenomena · Physics 2016-02-03 Yutaka Ohira

Electron acceleration to non-thermal, ultra-relativistic energies (~ 10-100 TeV) is revealed by radio and X-ray observations of shocks in young supernova remnants (SNRs). The diffusive shock acceleration (DSA) mechanism is usually invoked…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Mario A. Riquelme , Anatoly Spitkovsky

The subject of this paper is stochastic acceleration by plasma turbulence, a process akin to the original model proposed by Fermi. We review the relative merits of different acceleration models, in particular the so called first order Fermi…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Vahe Petrosian

We are able to detect the details of spatial optical collisionless wave-breaking through the high aperture imaging of a beam suffering shock in a fluorescent nonlinear nonlocal thermal medium. This allows us to directly measure how…

Optics · Physics 2014-03-05 N. Ghofraniha , L. Santamaria Amato , V. Folli , S. Trillo , E. DelRe , C. Conti

We have extended a simple model of nonlinear diffusive shock acceleration (Berezhko and Ellison 1999) to include the injection and acceleration of electrons and the production of photons from bremsstrahlung, synchrotron, inverse-Compton,…

Astrophysics · Physics 2009-10-31 Donald C. Ellison , Evgeny G. Berezhko , Matthew G. Baring

Energetic positrons have been observed in the interstellar medium, and high-energy positrons with relativistic energies up to approximately 1 TeV have been detected in Galactic cosmic rays. We conducted a study on the acceleration of…

High Energy Astrophysical Phenomena · Physics 2024-05-31 Huan Yu , Qi Xia , Jun Fang

Using the Monte Carlo simulations we apply a method of discrete small amplitude particle momentum scattering to reproduce highly anisotropic conditions at relativistic shocks. We discusse acceleration times scales in relativistic shocks.…

Astrophysics · Physics 2016-08-30 Janusz Bednarz

Collisionless regime kinetic models for coherent nonlinear Alfven wave dynamics are studied using fluid moment equations with an approximate closure anzatz. Resonant particle effects are modelled by incorporating an additional term…

Plasma Physics · Physics 2009-10-30 M. V. Medvedev , P. H. Diamond
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