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Title: Bernstein instability driven by thermal ring distribution

The classic Bernstein waves may be intimately related to banded emissions detected in laboratory plasmas, terrestrial, and other planetary magnetospheres. However, the customary discussion of the Bernstein wave is based upon isotropic thermal velocity distribution function. In order to understand how such waves can be excited, one needs an emission mechanism, i.e., an instability. In non-relativistic collision-less plasmas, the only known Bernstein wave instability is that associated with a cold perpendicular velocity ring distribution function. However, cold ring distribution is highly idealized. The present Brief Communication generalizes the cold ring distribution model to include thermal spread, so that the Bernstein-ring instability is described by a more realistic electron distribution function, with which the stabilization by thermal spread associated with the ring distribution is demonstrated. The present findings imply that the excitation of Bernstein waves requires a sufficiently high perpendicular velocity gradient associated with the electron distribution function.
Authors:
 [1] ;  [2] ; ;  [3]
  1. Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)
  2. (Korea, Republic of)
  3. Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan)
Publication Date:
OSTI Identifier:
22304112
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 7; Other Information: (c) 2014 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; BERNSTEIN MODE; DISTRIBUTION FUNCTIONS; INSTABILITY; PLANETARY MAGNETOSPHERES; PLASMA WAVES; RELATIVISTIC RANGE; VELOCITY