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Title: Wave-particle interactions with parallel whistler waves: Nonlinear and time-dependent effects revealed by particle-in-cell simulations

We present a self-consistent Particle-in-Cell simulation of the resonant interactions between anisotropic energetic electrons and a population of whistler waves, with parameters relevant to the Earth's radiation belt. By tracking PIC particles and comparing with test-particle simulations, we emphasize the importance of including nonlinear effects and time evolution in the modeling of wave-particle interactions, which are excluded in the resonant limit of quasi-linear theory routinely used in radiation belt studies. In particular, we show that pitch angle diffusion is enhanced during the linear growth phase, and it rapidly saturates well before a single bounce period. This calls into question the widely used bounce average performed in most radiation belt diffusion calculations. Furthermore, we discuss how the saturation is related to the fact that the domain in which the particles pitch angle diffuses is bounded, and to the well-known problem of 90° diffusion barrier.
Authors:
 [1] ;  [2]
  1. Center for Mathematics and Computer Science (CWI), 1098 XG Amsterdam (Netherlands)
  2. Department of Physics, University of Calabria, Ponte P. Bucci, Cubo 31C, I-87036 Rende (Italy)
Publication Date:
OSTI Identifier:
22490127
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANISOTROPY; DIFFUSION BARRIERS; INCLINATION; NONLINEAR PROBLEMS; PARTICLE INTERACTIONS; PLASMA SIMULATION; RADIATION BELTS; TAIL ELECTRONS; TEST PARTICLES; TIME DEPENDENCE; WHISTLERS