Simplified Model of Nonlinear Landau Damping

N. A. Yampolsky and N. J. Fisch

关键词: AMPLIFICATION;    AMPLITUDES;    DISTRIBUTION FUNCTIONS;    ELECTRONS;    KINETICS;    LANDAU DAMPING;    PHASE VELOCITY;    PLASMA WAVES;    SATURATION Nonlinear Theories;    Quaslinear Theories;    Viasov Equetion;   

DOI  :  10.2172/959129
RP-ID  :  PPPL-4426
PID  :  OSTI ID: 959129
Others  :  TRN: US1005725

学科分类：原子、分子光学和等离子物理

美国|英语

来源: SciTech Connect

【 摘 要 】

The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.