Study on RF Tandem Mirror

射频串联反射镜项目的主要目的是通过仅使用ICRF功率来演示纯轴对称磁场配置下的等离子体约束。我们已经发现，等离子体的产生、mhd稳定、离子加热以及堵塞和热障势的形成都可以通过中心射频和堵塞射频的结合来实现。氦等离子体由中心射频激发的螺旋/快波产生的峰值密度为1.8X10^<13>cm^<-3>， β值为- 10%。在双离子等离子体中，离子温度达到了Ti_1 - 220 eV，密度为0.4 × 10^<13>cm^<-3>。这种加热是由于螺旋/快波在混合共振时模式转换为慢阿尔芬波。等离子体是mhd稳定的，由于射频的重动机效应。中心射频在插头背板处产生电位倾斜。这种倾斜是由堵塞电池中少数离子加热产生的晃动离子分布形成的。观察到60- 80V的插头电位phi c导致端损磁通降低。轴向约束时间提高了2-3倍。通过对插头RF的额外应用，phi B - 90v的热障电位由phi c - 100v产生。phi B的值随着插头射频功率的增加而增加。势垒泵送很可能是由塞式电池RF的方位角质动势驱动的非双极性离子对流提供的。

The main purpose of the RF tandem mirror project is to demonstrate plasma confinement in purely axisymmetric magnetic field configuration by using ICRF power only. We have revealed that the plasma production, MHD-stabilization, ion heating, and plug and thermal barrier potential formation can all be achieved by a combination of the central RF and the plug RF.The highest peak density produced by the helicon/fast wave excited by the central RF is 1.8X10^<13>cm^<-3> with the beta value of - 10 % for helium plasma. In a two-ion-species plasma, ion temperatures of Ti_1 - 220 eV have been achieved at densities of 0.4x10^<13>cm^<-3>. This heating is due to the mode conversion of the helicon/fast wave into the slow Alfven wave at the hybrid resonance. The plasma is MHD-stable due to the RF ponderomotive effect. The central RF produces the potential dip at the plug midplane. This dip is formed by the sloshing ion distribution created by the minority ion heating in the plug cell. The plug potential phi c of 60- 80V is observed resulting in reduced end loss flux. The axial confinement time is improved by a factor of 2-3. By the additional application of the plug RF, the thermal barrier potential of phi B - 90 V is created with phi c - 100 V. The value of phi B increases with the plug RF power. it is likely that the barrier pumping is provided by the non-ambipolar ion convection driven by the azimuthal ponderomotive force of the plug cell RF.