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

非均匀磁场中阿尔文波的模式转换和微观不稳定性

基本信息

批准号：
02452270
负责人：
INUTAKE Masaaki
金额：
$ 2.82万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

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

四极锚细胞位于一个轴对称的中央细胞和轴对称的插头/势垒细胞之间的伽马10串联镜。在锚室的两侧存在回流过渡区，其中磁通管具有椭圆形横截面。在中心单元两端安装了可控制方位模m的ICRF天线，通过波场测量发现，在中心单元中激发的m=+1的右旋圆极化快Alfven波在锚单元中被有效地模转换为m=-1的左旋圆极化慢Alfven波。作为物理机制，提出了四重跃迁区磁通管的椭圆（m= /-2）调制引起的谐振模耦合引起模式转换的模型<plus-minus>。本文从理论上建立了耦合Alfven波方程，并在弱调制、周期四重光纤的假设下解析求解。 ...更多信息 eld.理论结果验证了上述转换模型的正确性，并指出快、慢Alfven波在没有四重波分量的情况下是不耦合的，它们是独立传播的。模式转换慢波的锚离子的共振加热直接证实与抗磁环。发现锚离子是由快波加热的，而不是由中心电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，确定了笛形交换模式的稳定边界，清楚地表明了串联镜中笛形模式的平均最小B稳定化的有效性。在ICRF HeaLed中央单元等离子体中，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，Alfven-ion-cyclotron（AIC）模式。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模式的波动和并发的高能量离子的损失增加到镜损失锥的压力各向异性的松弛已被观察到。少