部分球壳分布离子流激发的电磁不稳定性

在离子环束流和低频电磁波相互作用的过程中廓了环束流将演化成具有投掷角展宽的部分球壳速度分布离子流，其投掷角展宽随时间增大，低频右旋电磁不稳定性增长率峰值，总的说来也逐渐增大，并向高频短波方向移动，与此相反，低频左旋电磁不稳定性增长率峰值，当投掷 角展宽等于０时，大于右旋不稳定性峰值，但随着投掷角展宽增加而迅速低于右 性增长率峰值，并向工波方向移动。

ION RING-BEAM INSTABILITY DRIVEN BY IONS WITH A PARTIAL SHELL DISTRIBUTION

In the interaction between ion ring-beam and waves, the ring-beam velocitydistribution of the ions will evolve into a partial shell velocity distribution. Thespread of pitch angle of this partial shell increases with time, the peak value ofgrowth rate spectrum of the right hand ion beam instability decreases in generaland shifts to the region of higher frequency and larger wave number. The peakvalue of growth rate spectrum of the left hand instability driven by ions with aninitial ring distribution decreases rapidly with the increase of the spread of the pitchangle of the partial shell and shifts to the region of lower frequency and longer wavenumber.