用静电探针反馈控制KT-5C托卡马克边缘湍流

EDGE TURBULENCE CONTROL ON THE KT 5C TOKAMAK BY FEEDBACK USING ELECTROSTATIC PROBES

在ＫＴ－５Ｃ托卡马克上，利用两组边缘静电探针分别作为控制探针和探测探针进行了反馈控制边缘湍流的实验。在适当的回路增益下，当系统相移为９０ｏ时，反馈使湍动幅度明显地抑制，电子密度和电子温度扰动均降低了约２５％，横向粒子输运通量也相应地降低了２５％。而相移为０ｏ、１８０ｏ和－９０ｏ的反馈却使湍动幅度增强。这显示反馈是基于一种非线性机制而作用于湍动的，在一定意义上，这正体现了湍流本身的非线性特征。

Experiments on edge turbulence control have been performed on the KT 5C tokamak by feedback using two sets of electrostatic probes as the driving probe and detective probe.The results indicate that the feedback can enhance or reduce the turbulence amplitude depending upon the phase shift and gain of the feedback network.When the feedback with 90 o phase shift and with certain loop gain is applied,the spectrum component of turbulence is reduced obviously and the fluctuation amplitude of the electron density and electron temperature become lower by about 25%.Consistently the particle flux across the magnetic filed induced by the electrostatic fluctuation also decreases by about 25%.On the other hand,the feedback with 0 o or 180 o or -90 o phase shift can enhance the amplitude of the edge turbulence.These results indicate a nonlinear mechanism of the influence of feedback on the edge turbulence,which to some extent also reflect a specific nonlinear characteristic of the edge turbulence.