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Title: Electron-Ion collisions in relativistically strong laser fields

Abstract

Electron-ion collisions in relativistically strong electromagnetic fields are considered. Analytical and numerical analyses both show that all qualitative effects characteristic of collisions in nonrelativistic strong fields [1-3] occur at relativistic intensities of an electromagnetic wave as well. Expressions for Joule plasma heating and for the energy distributions of fast particles are derived from simple analytic considerations and are confirmed by numerical simulations. It is found, in particular, that, due to the relativistic increase in the mass of a scattered electron, Joule heating in ultrarelativistic fields becomes more intense as the field amplitude grows.

Authors:
 [1]
  1. Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)
Publication Date:
OSTI Identifier:
21100084
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 34; Journal Issue: 4; Other Information: DOI: 10.1134/S1063780X08040065; Copyright (c) 2008 Pleiades Publishing, Ltd; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; COMPUTERIZED SIMULATION; ELECTROMAGNETIC FIELDS; ELECTRON-ION COLLISIONS; ELECTRONS; ENERGY SPECTRA; JOULE HEATING; LASER RADIATION; MASS; NUMERICAL ANALYSIS; PARTICLES; RELATIVISTIC RANGE

Citation Formats

Balakin, A. A. Electron-Ion collisions in relativistically strong laser fields. United States: N. p., 2008. Web. doi:10.1134/S1063780X08040065.
Balakin, A. A. Electron-Ion collisions in relativistically strong laser fields. United States. doi:10.1134/S1063780X08040065.
Balakin, A. A. Tue . "Electron-Ion collisions in relativistically strong laser fields". United States. doi:10.1134/S1063780X08040065.
@article{osti_21100084,
title = {Electron-Ion collisions in relativistically strong laser fields},
author = {Balakin, A. A.},
abstractNote = {Electron-ion collisions in relativistically strong electromagnetic fields are considered. Analytical and numerical analyses both show that all qualitative effects characteristic of collisions in nonrelativistic strong fields [1-3] occur at relativistic intensities of an electromagnetic wave as well. Expressions for Joule plasma heating and for the energy distributions of fast particles are derived from simple analytic considerations and are confirmed by numerical simulations. It is found, in particular, that, due to the relativistic increase in the mass of a scattered electron, Joule heating in ultrarelativistic fields becomes more intense as the field amplitude grows.},
doi = {10.1134/S1063780X08040065},
journal = {Plasma Physics Reports},
number = 4,
volume = 34,
place = {United States},
year = {Tue Apr 15 00:00:00 EDT 2008},
month = {Tue Apr 15 00:00:00 EDT 2008}
}
  • The emission from an electron in the field of a relativistically strong laser pulse is analyzed. At pulse intensities of J>=2x10{sup 22} W/cm{sup 2} the emission from counterpropagating electrons is modified by the effects of quantum electrodynamics (QED), as long as the electron energy is sufficiently high: E>=1 GeV. The radiation force experienced by an electron is for the first time derived from the QED principles and its applicability range is extended toward the QED-strong fields.
  • Electron-ion collisions in plasma in a strong electromagnetic field are considered in the ultrarelativistic limit (in which the vector potential A is such that a = eA/mc{sup 2} >> 1). Expressions relating the electron drift coordinates and momentum to those in the laboratory frame are obtained using exact canonical transformations with allowance for adiabatic effects. The appearance of ultrafast particles with a maximum energy proportional to the third power of the laser pulse vector potential is predicted. Expressions for the energy (and number) distribution function of such high-energy (hot) electrons appearing as a result of electron-ion collisions are obtained. Thesemore » distribution functions obey a power law, which agrees with the results recently obtained by Mangles et al. in experiments with a petawatt laser.« less
  • Electron-ion collisions in the presence of a strong laser field lead to a distribution of fast electrons with maximum energy E{sub max}=(k{sub 0}+2v{sub 0}){sup 2}/2(a.u.), where k{sub 0} is the impact and v{sub 0} the quiver velocity of the electron. The energy spectrum is calculated by two approaches: (1) The time-dependent Schroedinger equation is numerically solved for wave packet scattering from a one-dimensional softcore Coulomb potential. Multiphoton energy spectra are obtained demonstrating a separation of the energy spectrum into an exponential distribution for transmission and a plateau distribution for reflection. (2) The energy spectrum is analytically calculated in the frameworkmore » of classical instantaneous Coulomb collisions with random impact parameters and random phases of the laser field. An exact solution for the energy spectrum is obtained from which the fraction of fast electrons in the plateau region can be estimated.« less
  • A method for obtaining exact periodic solutions of relativistically strong-coupled transverse-longitudinal waves in an electron-ion plasma is presented. Suitable choice of initial conditions yields wave solutions whose longitudinal component has twice the frequency of the transverse. In addition, the significance of the plasma stream velocity in the nonlinear theory is discussed.
  • The energy spectrum and angular distribution of electrons scattered by an ion in a strong laser field are investigated as a function of the incident electron velocity for small impact parameters. The energy distribution has been calculated quantum-mechanically by a method of wave-packet scattering from a three-dimensional hydrogen-like Coulomb potential. It is compared with the energy distribution from the classical instantaneous collision model, and the quantum limitations are evaluated. The backscattered particles can have enhanced scattering rates and a very large energy gain due to the effect of correlated collisions. Their spectrum displays a ring structure similar to the rescatteringmore » plateau in the above-threshold ionization of neutral atoms. The effect of these large-angle scattering effects on the electron acceleration and heating is also discussed.« less