Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA.
Zhejiang University, Hangzhou, Zhejiang 310027, China.
Phys Rev Lett. 2018 Jun 29;120(26):265001. doi: 10.1103/PhysRevLett.120.265001.
The effects of kinetic whistler wave instabilities on the runaway-electron (RE) avalanche is investigated. With parameters from experiments at the DIII-D National Fusion Facility, we show that RE scattering from excited whistler waves can explain several poorly understood experimental results. We find an enhancement of the RE avalanche for low density and high electric field, but for high density and low electric field the scattering can suppress the avalanche and raise the threshold electric field, bringing the present model much closer to observations. The excitation of kinetic instabilities and the scattering of resonant electrons are calculated self-consistently using a quasilinear model and local approximation. We also explain the observed fast growth of electron cyclotron emission signals and excitation of very low-frequency whistler modes observed in the quiescent RE experiments at DIII-D tokamak. Simulations using ITER parameters show that by controlling the background thermal plasma density and temperature, the plasma waves can also be excited spontaneously in tokamak disruptions and the avalanche generation of runaway electrons may be suppressed.
研究了动哨声波不稳定性对逃逸电子（RE）雪崩的影响。利用来自 DIII-D 国家核聚变设施实验的参数，我们表明，从受激哨声波散射的 RE 可以解释几个理解不佳的实验结果。我们发现，在低密度和高电场的情况下，RE 雪崩会增强，但在高密度和低电场的情况下，散射可以抑制雪崩并提高阈值电场，使目前的模型更接近观察结果。使用准线性模型和局部近似，自洽地计算了动不稳定性的激发和共振电子的散射。我们还解释了在 DIII-D 托卡马克的静止 RE 实验中观察到的电子回旋辐射信号的快速增长和甚低频哨声波模式的激发。使用 ITER 参数的模拟表明，通过控制背景热等离子体密度和温度，也可以在托卡马克中断中自发地激发等离子体波，并且可以抑制逃逸电子的雪崩产生。
