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Unstable ion cyclotron harmonic waves generated by inhomogeneity and the ion beam in an ion-beam–plasma system

Published online by Cambridge University Press:  01 February 2002

S. UTSUNOMIYA
Affiliation:
Department of Physics, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
S. IWAMOTO
Affiliation:
Department of Physics, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
T. KONDO
Affiliation:
Department of Physics, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
M. SUGAWA
Affiliation:
Department of Physics, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
T. MAEHARA
Affiliation:
Department of Physics, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
R. SUGAYA
Affiliation:
Department of Physics, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan

Abstract

In an ion-beam–inhomogeneous-plasma system, when the drift frequency ω* exceeds a harmonic of the ion cyclotron frequency nωci, ion cyclotron harmonic waves are excited via the plasma inhomogeneity. These waves are strongly enhanced by ion-beam injection parallel to the magnetic field. As the plasma inhomogeneity is increased, the number of unstable modes increases as does their amplitude. Ion cyclotron harmonic waves with frequencies up to 4ωci are observed experimentally; at least five modes become unstable, and these unstable waves have different az-imuthal mode numbers l = 1 or 2. The dispersion relations of observed multiple ion cyclotron harmonic waves agree well with the theoretical ones, taking into account the plasma inhomogeneity and the ion beam.

Type
Research Article
Copyright
2001 Cambridge University Press

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