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We examine the first order Fermi acceleration on the presumption that supernova remnant shocks cross ambient magnetic fields with various angles. These oblique shocks accelerate particles more efficiently than the parallel shocks and…

Astrophysics · Physics 2009-10-31 K. Kobayakawa , Y. S. Honda , T. Samura

The dynamics of a point charged particle which is driven by a uniform external electric field and moves in a medium of elastic scatterers is investigated. Using rudimentary approaches, we reproduce, in one dimension, the known results that…

Statistical Mechanics · Physics 2009-10-28 P. L. Krapivsky , S. Redner

When a charged particle penetrates through an optical interface, photon emissions emerge - a phenomenon known as transition radiation. Being paramount to fundamental physics, transition radiation has enabled many applications from…

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

High-resolution radio observations of nearby active galactic nuclei have revealed extended, limb-brightened structures in their inner jets. This ties in with other multi-wavelength observations from radio to X-ray and gamma-ray, indicating…

High Energy Astrophysical Phenomena · Physics 2024-04-15 Jieshuang Wang , Frank M. Rieger , Yosuke Mizuno

Propagation of a particle accelerated by an external field through a scattering medium is studied within the generalized Lorentz model allowing inelastic collisions. Energy losses at collisions are proportional to $(1-\alpha^{2})$, where…

Statistical Mechanics · Physics 2015-06-25 Ph. A. Martin , J. Piasecki

A comprehensive review is given of the various processes proposed for accelerating particles by shocks to high energies. These energies are limited by several bounds: the non-relativistic nature of the heliospheric collisionless shocks to…

Astrophysics · Physics 2008-06-26 R. A. Treumann , C. H. Jaroschek

The non-thermal particle spectra responsible for the emission from many astrophysical systems are thought to originate from shocks via a first order Fermi process otherwise known as diffusive shock acceleration. The same mechanism is also…

High Energy Astrophysical Phenomena · Physics 2015-06-12 B. Reville , A. R. Bell , G. Gregori

We present a detailed perturbative study of the dynamics of several types of atom-atom correlations in the famous Fermi problem. This is an archetypal model to study micro-causality in the quantum domain where two atoms, the first initially…

Magnetic Reconnection is an efficient and fast acceleration mechanism by means of direct electric field acceleration parallel to the magnetic field. Thus, acceleration of particles in reconnection regions is a very important topic in plasma…

Astrophysics · Physics 2015-06-24 Rudiger Schopper , Guido T. Birk , Harald Lesch

Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares. We present here self-consistently combined Fokker-Planck modeling of particles and hydrodynamic…

Solar and Stellar Astrophysics · Physics 2009-09-28 Wei Liu , Vahe Petrosian , John T. Mariska

Ultrafast electron beams are essential for many applications, yet space-charge interactions in high-intensity beams lead to energy dissipation, coherence loss, and pulse broadening. Existing techniques mitigate these effects by using…

Optics · Physics 2025-07-02 Hao Geng , Qiaofei Pan , Jian Kang , Yiming Pan

We study the acceleration of charged particles by ultra-relativistic shocks using test-particle Monte-Carlo simulations. Two field configurations are considered: (i) shocks with uniform upstream magnetic field in the plane of the shock, and…

High Energy Astrophysical Phenomena · Physics 2023-05-15 Zhi-Qiu Huang , Brian Reville , John G. Kirk , Gwenael Giacinti

We tackle the problem of the accelerating universe by reconsidering the most general form of the metric when the speed of light is allowed to evolve with time in a homogeneous and isotropic universe. A new varying speed of light (VSL) model…

General Relativity and Quantum Cosmology · Physics 2007-07-17 Corrado Appignani

We review the theory of interacting Fermi systems whose low-energy physics is governed by forward scattering, i.e. scattering processes generated by effective interactions with small momentum transfers. These systems include Fermi liquids…

Condensed Matter · Physics 2007-05-23 W. Metzner , C. Castellani , C. Di Castro

We give a new coherent description of the first-order Fermi acceleration of particles in shock waves from the point of view of stochastic process of the individual particles, under the test particle approximation. The time development of…

Astrophysics · Physics 2009-11-07 Tsunehiko N. Kato , Fumio Takahara

This work provides a concrete implementation of E. Fermi's model of particle acceleration in magnetohydrodynamic (MHD) turbulence, connecting the rate of energization to the gradients of the velocity of magnetic field lines, which it…

High Energy Astrophysical Phenomena · Physics 2022-11-30 Martin Lemoine

Shear flows are ubiquitously present in space and astrophysical plasmas. This paper highlights the central idea of the non-thermal acceleration of charged particles in shearing flows and reviews some of the recent developments. Topics…

High Energy Astrophysical Phenomena · Physics 2019-09-17 Frank M. Rieger

Charged particles are constantly accelerated to non-thermal energies by the reconnecting magnetic field in the solar atmosphere. Our understanding of the interactions between the particles and their environment can benefit from…

Solar and Stellar Astrophysics · Physics 2024-01-05 L. Frogner , B. V. Gudiksen

The rate at which particles are accelerated by the first-order Fermi mechanism in shocks depends on the angle, \teq{\Tbone}, that the upstream magnetic field makes with the shock normal. The greater the obliquity the greater the rate, and…

Astrophysics · Physics 2009-10-28 D. C. Ellison , M. G. Baring , F. C. Jones