Mode Conversion of Alfven Waves and Microinstabilities in a Non-uniform Magnetic Field

四极锚定单元位于GAMMA10串联反射镜的轴对称中心单元和轴对称堵塞/屏障单元之间。锚胞两侧有再循环过渡区，其中磁通管的横截面呈椭圆形。ICRF天线，其方位模式m可以控制，安装在中心小区的两端附近。从波场测量中发现，在中心单元中激发的右圆极化m=+ 1的快Alfven波在锚单元中有效地模式转换为左圆极化m=- 1的慢Alfven波。提出了四重跃迁区磁通管的椭圆（m=<正负>/-2）调制引起的谐振模式耦合引起模式转换的物理机理模型。本文从理论上推导了耦合阿尔芬波方程，并在弱调制周期性四倍频场的假设下对其进行了解析求解。理论结果验证了上述转换模型，说明在没有四重分量的情况下，快慢Alfven波不会相互耦合，而是独立传播。用反磁环直接证实了模式转换慢波对锚离子的共振加热。研究发现，锚离子在中心槽内受快波加热，而不是受慢波加热，因此转换效率应该很高。此外，通过改变锚定β值确定了长笛交换模式的稳定边界，清楚地证明了串联镜像中长笛模式平均最小b稳定的有效性。微观不稳定性，在具有压力各向异性的高β等离子体中预期的alfven -离子回旋（AIC）模式已经在icrf愈合的中央细胞等离子体中被确定。观测到的磁场波动强烈依赖于温度各向异性和β值。由于AIC模式的波动导致压力各向异性的松弛，并同时增加了进入镜面损失锥的高能离子损失。少

The quadrupole anchor cells are located between an axisymmetric central cell and axisymmetric plug /barrier cells in the GAMMA10 tandem mirror. There are recircularizing-transition regions on both sides of the anchor cell, where The magnetic flux tube has an elliptical cross section. ICRF antennas, of which azimuthal mode m can be controlled, are installed near both ends of the central cell.It is found from wave-field measurements that a right-circularly polarized, m=+l fast Alfven wave excited in the central cell is efficiently mode converted to a left-circularly-polarized, m=-l slow Alfven wave in the anchor cell. As a physical mechanism is proposed a model that the mode conversion is brought about by a resonant mode coupling caused by the elliptical (m=<plus-minus>/-2) modulation of the flux tube in The quadruple transition region. Coupled-Alfven-wave equations are theoretically formulated, and are analytically solved under The assumption of a weakly-modulated, periodic quadruple fi … More eld. Theoretical results validate the above conversion model and tell that fast and slow Alfven waves do not couple with each other without the quadruple component and propagate independently. Resonant heating of the anchor ions by the mode-converted slow wave is directly confirmed with diamagnetic loops. It is found that the anchor ions are heated by the fast wave, not by the slow wave excited in the central cell and thus the conversion efficiency should be very high. Moreover, a stability boundary for the flute interchange mode has been identified by varying the anchor beta value, clearly demonstrating the validity of the averaged minimum-B stabilization of a flute mode in a tandem mirroA microscopic instability, Alfven-ion-cyclotron (AIC) mode, expected in a high beta plasma with pressure anisotropy, has been identified in the ICRF-heaLed central-cell plasmas. Observed magnetic field fluctuations strongly depend on the temperature anisotropy and the beta value. Relaxation of the pressure anisotropy due to the AIC mode fluctuations and the concurrent increase of high energy ion loss into the mirror loss cone have been observed. Less