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Title: Effects of passing energetic particles on geodesic acoustic mode

Effects of passing energetic particles on geodesic acoustic modes (GAMs) are investigated using the hybrid kinetic-fluid model. The local dispersion relation of GAM is derived by adopting the equilibrium distribution function for slowing-down energetic ions with a single pitch angle. The dependence of the distribution function on the poloidal angle is first taken into account and shows to play a crucial role in determining the instability criterion as well as the frequency of GAM, although the poloidal asymmetry is of order O(ϵ). A high frequency branch of GAM resonantly excited is always stable, and a low frequency branch could be unstable. The case of zero pitch angle is specifically discussed. This case is always responsible for stable modes when disregarding the poloidal asymmetry, but can be unstable when the poloidal asymmetry is considered.
Authors:
;  [1]
  1. Department of Modern Physics, The Collaborative Innovation Center for Advanced Fusion Energy and Plasma Science, University of Science and Technology of China, Hefei 230026 (China)
Publication Date:
OSTI Identifier:
22299677
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 10; 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; ASYMMETRY; DISPERSION RELATIONS; DISTRIBUTION FUNCTIONS; EQUILIBRIUM; INCLINATION; PLASMA INSTABILITY; SLOWING-DOWN; TAIL IONS