Simulation of linear and nonlinear Landau damping of lower hybrid waves

Journal Article · Sat Jun 15 04:00:00 EDT 2013 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4812196· OSTI ID:22228019

Qi, Lei; Wang, X. Y.; Lin, Y. ^[1]

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1. Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

The linear physics of lower hybrid waves (LHWs) and their nonlinear interaction with particles through Landau damping are studied with the gyrokinetic electron and fully kinetic ion (GeFi) particle simulation model in the electrostatic limit. Unlike most other wave modes, the LHWs can resonantly interact with both electrons and ions, with the former being highly magnetized and latter nearly unmagnetized around the lower hybrid frequency. Direct interactions of LHWs with electrons and/or ions are investigated for cases with various k{sub ∥}/k,T{sub i}/T{sub e}, and wave amplitudes. In the linear electron Landau damping (ELD), the dispersion relation and the linear damping rate obtained from our simulation agree well with the analytical linear theory. As the wave amplitude increases, the nonlinear Landau effects are present, and a transition from strong decay at smaller amplitudes to weak decay at larger amplitudes is observed. In the nonlinear stage, the LHWs in the long time evolution finally exhibit a steady Bernstein-Greene-Kruskal mode, in which the wave amplitude is saturated above the noise level. While the resonant electrons are trapped in the wave field in the nonlinear ELD, the resonant ions are untrapped in the LHW time scales. The ion Landau damping is thus predominantly in a linear fashion, leading to a wave saturation level significantly lower than that in the ELD. On the long time scales, however, the ions are still weakly trapped. The results show a coupling between the LHW frequency and the ion cyclotron frequency during the long-time LHW evolution.

• OSTI ID: 22228019
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 20; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CYCLOTRON FREQUENCY
DISPERSION RELATIONS
ELECTRONS
IONS
LANDAU DAMPING
LOWER HYBRID CURRENT DRIVE
LOWER HYBRID HEATING
NONLINEAR PROBLEMS
PLASMA
PLASMA SIMULATION
TRAPPING