Electron Heating and Potential Formation due to Mode Conversion of ICRF Fast Waves

在HIEI串联反射镜中研究了注入中心细胞的ICRF波对离子限制电位形成的影响。波的传播测量结果表明，快速磁声波在高场侧与离子-离子混合共振层接触后，会转化为具有共振现象的静电波。在这种情况下，在对原子发射线强度的测量中观察到塞子电池中电子温度的升高。同时，末端损耗能量分析仪的测量结果表明，形成了离子限制电位（- 70 V）。轴向粒子约束时间增加了3-4倍，减少了末端离子损失，增加了中心细胞的密度。电势形成的机制是电子在ICRF波作用下的空间扩散速度。在这种改进的轴向约束和通过限制器偏置改进的径向约束的组合中(物理评论快报，Vol.70(1993)pp。4071-4074)，实现了高温（离子温度：0.1 keV）和高密度（10^<13>cm^<-3>）等离子体，其中β值达到- 14%。整体能量约束时间增加了-4倍，其中轴向和径向能量约束时间分别增加了3.8倍和4.0倍。这种高β等离子体的产生是由于对全局约束的增强。这种高β等离子体通过传播ICRF电场的重力动势维持在稳定标准内。我们得出结论，由于ICRF快波的模式转换导致的电子加热和电势形成对串联反射镜的约束增强是有效的。

Effects of an ICRF wave injected into the central cell for formation of the ion confining potential were investigated in the HIEI tandem mirror. Measurements on wave propagation revealed that the fast magnetosonic wave propagating into the plug cell converts into an electrostatic wave with resonance phenomenon when it encounters the ion-ion hybrid resonance layr from the high-field side. In this case, rise of electron temperature in the plug cell was observed in the measurement on intensities of atomic emission lines. Simultaneously, measurements by the end loss energy analyzer showed that the ion confining potential (- 70 V) is formed. The axial particle confinement time was found to increase by a factor of 3-4, which leads to reduction of the end ion loss and density increase in the central cell. The mechanism of potential formation would be the velocity space diffusion of electrons by ICRF waves.In the combination of such an improved axial confinement and the improved radial confinement by the limiter biasing (Physical Review Letters, Vol.70(1993)pp.4071-4074), a plasma with high temperature (ion temperature : 0.1 keV) and high density (10^<13>cm^<-3>) was realized, where the beta valuereaches - 14%. The global energy confinement time increases by a factor of -4, where the axial and radial energy confinement times increase by a factor of 3.8 and 4.0, respectively. The production of such a high-beta plasma results from the enhancement on the global confinement. This high-beta plasma is sustained within the stability criteria by ponderomotive force of propagating ICRF electric fields.We have concluded that electron heating and potential formation due to mode conversion of the ICRF fast wave is effective on the enhancement on confinement of a tandem mirror.