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Title: Pitch-angle scattering of energetic particles with adiabatic focusing

Understanding turbulent transport of charged particles in magnetized plasmas often requires a model for the description of random variations in the particle's pitch angle. The Fokker-Planck coefficient of pitch-angle scattering, which is used to describe scattering parallel to the mean magnetic field, is therefore of central importance. Whereas quasi-linear theory assumes a homogeneous mean magnetic field, such a condition is often not fulfilled, especially for high-energy particles. Here, a new derivation of the quasi-linear approach is given that is based on the unperturbed orbit found for an adiabatically focused mean magnetic field. The results show that, depending on the ratio of the focusing length and the particle's Larmor radius, the Fokker-Planck coefficient is significantly modified but agrees with the classical expression in the limit of a homogeneous mean magnetic field.
Authors:
 [1] ;  [2] ;  [3]
  1. Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin (Germany)
  2. Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada)
  3. Center for Space Plasmas and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States)
Publication Date:
OSTI Identifier:
22370407
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CHARGED PARTICLES; CHARGED-PARTICLE TRANSPORT; COSMIC RADIATION; DIFFUSION; FOKKER-PLANCK EQUATION; INCLINATION; LARMOR RADIUS; MAGNETIC FIELDS; ORBITS; PARTICLES; PLASMA; RANDOMNESS; SCATTERING; TURBULENCE; VARIATIONS