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Title: Alfvén ion-cyclotron instability in an axisymmetric trap with oblique injection of fast atoms

Conditions for the onset of Alfvén ion-cyclotron instability and the spatial structure of unstable modes in an axisymmetric mirror trap with oblique injection of fast atoms are studied. It is shown that the main contribution to instability comes from the inverse population of ions in the velocity space domain into which atoms are injected. Using the distribution function of fast ions obtained by approximately solving the Fokker-Planck equation, the instability threshold in terms of β{sub ⊥} is determined in the Wentzel-Kramers-Brillouin approximation as a function of the geometric parameters and the parameters of injection and target plasma. It is demonstrated that the stability threshold increases substantially when the radius of the hot plasma decreases to a size comparable with the Larmor radius of fast ions. It is shown that the perturbed fields near the axis and at the plasma periphery can rotate in opposite directions, which is important for the interpretation of experimental data.
Authors:
;  [1]
  1. Russian Academy of Sciences, Budker Institute of Nuclear Physics (Russian Federation)
Publication Date:
OSTI Identifier:
22314722
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 40; Journal Issue: 12; Other Information: Copyright (c) 2014 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALFVEN WAVES; AXIAL SYMMETRY; CYCLOTRON INSTABILITY; DISTRIBUTION FUNCTIONS; FOKKER-PLANCK EQUATION; HOT PLASMA; LARMOR RADIUS; WKB APPROXIMATION