测地声模连续谱参量激发过程的数值研究

Numerical Study of the Parametric Excitation of the Geodesic Acoustic Mode Continuum by Drift Wave

摘要: 为了验证Yu和Dong给出的解析结果的合理性，用数值计算的方法对离子温度为非均匀的等离子体中测地声模连续谱的非线性激发过程进行了研究。数值计算的结果表明，漂移波边带模的径向结构分布图与简谐振荡都很接近，这说明Yu和Dong对参量激发方程的解析求解的出发点是合理的。对于一定的离子温度分布，在一定共振频率的条件下，测地声模连续谱的增长率与漂移波的振幅的平方成正比，这和Yu和Dong给出的相关的解析结果的结论一致。根据所求出的漂移波边带模的径向分布，可以计算出测地声模的径向结构分布。计算的结果表明，测地声模连续谱的振幅在共振点附近具有最大值。

Abstract: The growth rate of the geodesic acoustic mode and the radial structures of the sideband drift waves and the geodesic acoustic modes continuum are studied as a parametric process in the tokamak plasmas with a non-uniform ion temperature profile for which the non-uniform part of the inherent geodesic acoustic mode frequency takes the form of sin function. It is shown that the radial structures of the drift wave sideband are close to the harmonic function, the en- ergies of the geodesic acoustic modes are mainly localized around the resonant points of the parametric excitations, and the growth rate is proportional to the square of the amplitude of the pump wave, which indicates that the corresponding analytical results is reasonable.