Formation of Plasma potential by means of ECH at divertor and peripheral region of plasma

等离子体的稳定是通过电子回旋加热（ECH）产生等离子体电位或控制压力分布来实现的。计划并完成了(1)等离子体内区、(2)外周区和(3)导流区的ECH实验。结果总结如下：(1)在强磁场和（或）较低电子密度的情况下，低杂波（LHW）可以传播到等离子体内部，在等离子体内部由LH电流驱动（LHCD）抑制撕裂不稳定，从而产生新的MIHD不稳定，实验结果表明这种不稳定是一种压力驱动模式，通过ECH控制压力剖面对这种模式的抑制是非常有效的。(2)在高电子密度的情况下，等离子体的环向旋转被LHCD减慢，撕裂模式被锁模到真空容器，最终发生等离子体破坏。等离子体旋转的减缓表明等离子体电位的降低，这可能是由于等离子体外围的LHCD驱动的快速电子的损失。ECH对于解锁模式和恢复等离子体环向旋转是非常有效的。因此，可以避免等离子体的破坏。这些结果表明ECH对恢复电位是有效的。(3)考虑到利用电子伯恩斯坦波对导流区附近的低温等离子体有较好的ECH效果，我们制备了加热mm波电源，并设计了伯恩斯坦波加热的传输线和注入天线。在该方案中，环形波纹中的捕获电子可被加热并通过环形漂移注入主等离子体，并在等离子体外围区形成等离子体势。

Stabilization of plasma has been attained via formation of plasma electric potential or control of pressure profile by means of electron cyclotron heating (ECH). ECH experiments on (1) inner region of plasma, (2) peripheral region and (3) divertor region were planned and done. The results are summarized as follows.(1) In the case of strong magnetic field and/or relatively low electron density, lower hybrid wave (LHW) can propagate into the inner side of plasma, where the tearing instability is suppressed by LH current drive (LHCD) and then a new MIHD instability is destabilized, The experimental results show that this instability is a pressure driven mode and pressure profile control by ECH is quite effective for suppression of the mode.(2) In the case of high electron density, toroidal rotation of plasma is slowed down by LHCD and the tearing mode is mode-locked to the vacuum vessel, and finally plasma disruption takes place. The slowdown of plasma rotation suggests the decrease of plasma potential, which may be ascribed to the loss of LHCD driven fast electrons at the plasma periphery. ECH is quite effective for unlocking of the mode lock and recovery of the plasma toroidal rotation. As a result, the plasma disruption can be avoided. These results suggests that ECH is effective for recovering of potential.(3) Since ECH by using Electron Bernstein waves is assumed to be quite effective for low electron temperature plasma near the divertor region, we have prepared a heating mm wave power source and designed the transmission line and injection antenna for the Bernstein wave heating. In this scheme, trapped electrons in toroidal ripple may be heated and injected into the main plasma via toroidal drift, and plasma potential may be formed at the j3lasma peripheral region.