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

在GAMMA10串联镜中，四极锚单元位于轴对称的中心单元和轴对称的塞/障单元之间。锚室两侧有再循环过渡区，其中磁通管的横截面为椭圆形。在中心小区的两端附近安装了方位模m可控的射频天线，通过波场测量发现，在中心小区激发的右圆极化m=L快阿尔芬波有效地转换为锚小区中的左圆极化m=-L慢阿尔芬波。作为一种物理机制，提出了一个模型，即模式转换是由四个过渡区的通量管的椭圆(m=正负/-2)调制引起的共振模式耦合。从理论上建立了耦合阿尔芬波方程，并在弱调制周期四倍频…的假设下进行了解析求解。年纪更大了。理论结果验证了上述转换模型，表明快慢Alfven波在没有四重分量的情况下并不相互耦合，相互独立地传播。模变换慢波对锚定离子的共振加热直接用反磁环证实。研究发现，锚离子是由快波加热的，而不是由中心池中激发的慢波加热的，因此转换效率应该很高。此外，通过改变锚β值确定了长笛交换模式的稳定性边界，清楚地证明了串联镜中长笛模式的平均最小B稳定化的有效性。在ICRF治愈的中央细胞等离子体中，已经确定了在具有压力各向异性的高β等离子体中预期的微观不稳定性，即阿尔芬离子回旋加速器(AIC)模式。观测到的磁场波动强烈地依赖于温度各向异性和贝塔值。观察到由于AIC模起伏引起的压力各向异性的松弛，同时增加了进入镜面损失锥的高能离子损失。较少

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