磁化等离子体里高频模和低频模耦合的参量不稳定性

用“有质动力”的方法,对一个空间均匀的磁化等离子体,在大振幅泵浦波E₀(r,t)作用下,推导了非线性色散关系。从这个色散关系出发,统一处理了各种常见波的参量激发,如反常吸收与反常散射,并与别人用其他方法计算的结果作了比较。发现只要在有质动力适用的条件下,我们的色散关系可以重新得到他们的结果。此外,我们还计算了几种还未见发表过的参量激发。从我们的结果可以看出,对反常吸收,“偶极近似”的做法基本上可以给出正确的结果。对反常散射,等离子体磁化后,阈值会提高,增长率会下降。所以磁场对受激散射型的参量激发起稳定作用。 关键词：

PARAMETRIC INSTABILITIES WITH WELL SEPARATED FREQUENCIES IN MAGNETIZED PLASMA

A nonlinear dispersion relation is derived for the homogeneous, magnetized plasmas by the conventional "ponderomotive force" method. By using this unified dispersion relation, various parametric instabilities (stimulated anomalous absorptions and scatterings) are discussed. The results are compared with those obtained by other authors in detail. In the validity region of this model ω_idler《 ω_pump), the results derived by previous authors can be recovered. In addition to obtaining a few instabilities which have not been appeared in literature, we also find that in general:1. the "dipole approximation" can give the right results for the stimulated anomalous absorption problems,2. the magnetic field may enhance the plasma stability.