It is shown that plasma turbulence at the edge of a fusion machine can lead to significant broadening of an X-mode microwave beam, which also impacts the performance of the heating systems and diagnostics. Based on a similar method developed for O-mode polarization, the expression for the mean microwave power distribution after the beam passes through the plasma edge turbulence is obtained, and its spatial and probabilistic distributions are analyzed. As this polarization is used for collective Thomson scattering (CTS) on ITER and for electron cyclotron resonance heating (ECRH) on ASDEX Upgrade, numerical simulations of beam broadening due to the edge turbulence are performed for the two conditions of plasma parameters, related to the planned CTS experiments on ITER and to ECRH experiments on ASDEX Upgrade. Ideas to reduce the beam broadening induced by the edge turbulence in the CTS case have been tested and are summarized in the conclusion.
摘要：研究表明，聚变装置边缘的等离子体湍流可导致X模微波束显著展宽，这也会影响加热系统与诊断系统的性能。基于为O模偏振发展的一种类似方法，本文推导了波束穿过边缘湍流后的平均功率分布表达式，并分析了其空间分布与概率分布特性。由于该偏振用于ITER上的联合汤姆孙散射（CTS）以及ASDEX Upgrade上的电子回旋共振加热（ECRH），因此针对计划中的ITER CTS实验和ASDEX Upgrade ECRH实验所对应的两种等离子体参数条件，开展了边缘湍流引起的波束展宽数值模拟。针对CTS情形下边缘湍流导致的波束展宽，本文测试了若干抑制方案，并在结论中进行了总结。