Generation and termination of runaway electrons at major disruptions in JT-60U
Generation and termination of runaway electrons at major disruptions in JT-60U
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DOI：
10.1088/0029-5515/39/2/302
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发表时间：
1999-02
期刊：
影响因子：
3.3
通讯作者：
R. Yoshino;S. Tokuda;Y. Kawano
中科院分区：
文献类型：
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作者：
R. Yoshino;S. Tokuda;Y. Kawano
研究了JT-60U型托卡马克等离子体在大干扰下避免失控电子产生的操作条件。已经发现，在低Bt的情况下，没有观察到失控电子。2.2 ?T或低等离子体电流猝灭率(I？？ -(dIp/dt)/Ip) < 50s -1。此外，没有观察到在等离子体边缘（qeff）定义的低有效安全系数。2.5甚至是高I？300 - 400年的?s-1，这是伴随着大等离子体位移（例如垂直位移事件（VDEs））的不受控制的破坏的情况。另一方面，在小等离子体位移的受控中断中，qeff很容易增加到8以上，并且即使在50-100 μ s-1的低电流淬火速率下也会观察到失控电子。此外，已经发现在这些位置控制的中断中，失控电流尾巴即使在等离子体表面电压为零或弱正的情况下也能迅速衰减。这些对逃逸电子的避免和终止的观察提示了逃逸电子的异常损失机制。
The operation conditions to avoid runaway electron generation at the major disruption have been investigated in JT-60U tokamak plasmas. It has been found that runaway electrons are not observed for low Bt of ? 2.2?T or low plasma current quench rates (I? ? -(dIp/dt)/Ip) of <50?s-1. Furthermore, they are not observed for low effective safety factors defined at the plasma edge (qeff) of ? 2.5 even for high I? of 300-400?s-1, which is the case for uncontrolled disruptions accompanied by large plasma displacements (e.g., vertical displacement events (VDEs)). On the other hand, in controlled disruptions with small plasma shifts, qeff easily increases above 8, and runaway electrons are observed even for low current quench rates of 50-100?s-1. Furthermore, it has been found that in these position controlled disruptions the runaway current tail can rapidly decay even for zero or weakly positive plasma surface voltages. These observations of the avoidance and termination of runaway electrons suggest an anomalous loss mechanism for runaway electrons.