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In this paper we study the application of a simplified method to solve the dynamic radiative transfer problem in expanding envelopes. The method, which requires a computational effort similar to that of the diffusion approximation, is based…

Astrophysics · Physics 2009-10-28 J. Gomez-Gomar , J. Isern

Modern electron linear accelerators are often designed to produce smooth bunch distributions characterized by their macroscopic ensemble-average moments. However, an increasing number of accelerator applications call for finer control over…

Accelerator Physics · Physics 2022-06-15 G. Ha , K. -J. Kim , P. Piot , J. G. Power , Y. Sun

A possible route towards achieving high power microwave (HPM) devices is through the use of novel slow-wave structures, represented by multiple coupled transmission lines (MTLs), and whose behavior when coupled to electron beams has not…

Plasma Physics · Physics 2013-10-25 Venkata Ananth Tamma , Filippo Capolino

We study the problem of particles undergoing Brownian motion in an expanding sphere whose surface is an absorbing boundary for the particles. The problem is akin to that of the diffusion of impurities in a grain of polycrystalline material…

Statistical Mechanics · Physics 2009-11-13 Karl Forsberg , Ali R. Massih

Shear flows are naturally expected to occur in astrophysical environments and potential sites of continuous non-thermal Fermi-type particle acceleration. Here we investigate the efficiency of expanding relativistic outflows to facilitate…

High Energy Astrophysical Phenomena · Physics 2016-12-14 F. M. Rieger , P. Duffy

Space-charge-induced emittance growth is a big con-cern for designing low energy and high intensity linacs. The Equipartitioning Principle was introduced to mini-mize space-charge-induced emittance growth by remov-ing free energy between…

Accelerator Physics · Physics 2021-05-18 Chuan Zhang

We introduce a description of the collective transverse dynamics of charged (proton) beams in the stability regime by suitable classical stochastic fluctuations. In this scheme, the collective beam dynamics is described by time--reversal…

Statistical Mechanics · Physics 2009-11-10 Nicola Cufaro Petroni , Salvatore De Martino , Silvio De Siena , Fabrizio Illuminati

A stochastic EDQNM approach is used to investigate self-similar decaying isotropic turbulence at high Reynolds number ($400 \leq Re_\lambda \leq 10^4$). The realistic energy spectrum functional form recently proposed by Meyers & Meneveau is…

Fluid Dynamics · Physics 2013-09-25 Marcello Meldi , Pierre Sagaut , Didier Lucor

The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by…

Accelerator Physics · Physics 2014-09-25 C. A. Ekdahl , B. T. McCuistian , M. E. Schulze , C. A. Carlson , D. K. Frayer , C. Mostrum , C. H. Thoma

A synthesis of the present knowledge on gamma-ray emission from the magnetosphere of a rapidly rotating neutron star is presented, focusing on the electrodynamics of particle accelerators. The combined curvature, synchrotron, and…

Astrophysics · Physics 2009-11-11 Kouichi Hirotani

We consider a kinetic equation describing evolution of a particle distribution function in a system with nonlinear wave-particle interactions (trappings into a resonance and nonlinear scatterings). We study properties of its solutions and…

Plasma Physics · Physics 2019-05-22 A. V. Artemyev , A. I. Neishtadt , A. A. Vasiliev

This paper presents a brief review of the newly developed \emph{Extended Electrodynamics}. The relativistic and non-relativistic approaches to the extension of Maxwell equations are considered briefly, and the further study is carried out…

High Energy Physics - Theory · Physics 2007-05-23 Stoil Donev , Maria Tashkova

Statistical fragment emission from excited nuclear systems is studied within the framework of a schematic Fermi-gas model combined with Weisskopf's detailed balance approach. The formalism considers thermal expansion of finite nuclear…

Nuclear Theory · Physics 2009-11-07 Jan Tõke , Jun Lu , W. Udo Schröder

We prove a central limit theorem for the momentum distribution of a particle undergoing an unbiased spatially periodic random forcing at exponentially distributed times without friction. The start is a linear Boltzmann equation for the…

Mathematical Physics · Physics 2015-05-14 Jeremy Clark , Christian Maes

Stochastic acceleration of charged particles due to interactions with magnetohydrodynamic (MHD) plasma waves is the dominant process leading to the formation of the high-energy electron and ion distributions in a variety of astrophysical…

Astrophysics · Physics 2008-11-26 P. A. Becker , T. Le , C. D. Dermer

We analyse the influence of the stochastic particle acceleration for the evolution of the electron spectrum. We assume that all investigated spectra are generated inside a spherical, homogeneous source and also analyse the synchrotron and…

Astrophysics · Physics 2009-11-11 K. Katarzynski , G. Ghisellini , A. Mastichiadis , F. Tavecchio , L. Maraschi

In this series of papers, we investigate the spreading and vanishing dynamics of time almost periodic diffusive KPP equations with free boundaries. Such equations are used to characterize the spreading of a new species in time almost…

Dynamical Systems · Mathematics 2015-07-08 Fang Li , Xing Liang , Wenxian Shen

A rigorous theory of diffraction scattering from extended objects is proposed. The present theory is based on a multiple asymptotic expansion of an integral equation for the exact wave function in terms of the large parameters of the…

Other Condensed Matter · Physics 2016-06-17 Gennady V. Kovalev

We discuss the diffusion phenomenon in the parabolic and hyperbolic regimes. New effects related to the finite velocity of the diffusion process are predicted, that can partially explain the strange behavior associated to adsorption…

Mathematical Physics · Physics 2014-02-13 A. Sapora , M. Codegone , G. Barbero

A simple model accounting for the ejection of heavy particles from the vortical structures of a turbulent flow is introduced. This model involves a space and time discretization of the dynamics and depends on only two parameters: the…

Chaotic Dynamics · Physics 2009-11-13 Jeremie Bec , Raphael Chetrite