Pitch-angle scattering of energetic particles with adiabatic focusing

Journal Article · Mon Oct 20 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/794/2/138· OSTI ID:22370407

Tautz, R. C. ^[1]; Shalchi, A. ^[2]

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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)

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.

• OSTI ID: 22370407
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 794; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CHARGED PARTICLES
CHARGED-PARTICLE TRANSPORT
COSMIC RADIATION
DIFFUSION
FOKKER-PLANCK EQUATION
INCLINATION
LARMOR RADIUS
MAGNETIC FIELDS
ORBITS
PARTICLES
PLASMA
RANDOMNESS
SCATTERING
TURBULENCE
VARIATIONS