ASDEX Upgrade中氩致破裂中逃逸电子产生的动力学模拟
Kinetic modelling of runaway electron generation in argon-induced disruptions in ASDEX Upgrade
摘要：
大量的材料注入已经被提出作为一种方法来减轻形成的相对论逃逸电子束，可能会导致在托卡马克等离子体中断。在本文中，我们分析了在11个ASDEX升级放电中观察到的失控生成，其中使用大量气体注入触发中断。我们提出了数值模拟的情况下，在轴上等离子体条件的特点，实验观测的约束下，使用的描述与自洽电场和温度演化的失控动力学在二维动量空间和零维真实空间。我们描述的电子分布函数的演变过程中的中断，并显示，失控的种子代占主导地位的热尾在所有的模拟放电。我们重现所观察到的依赖性的电流耗散率在失控的平台阶段的注入氩气的量。我们的模拟还表明，在注入氩气的阈值量以上，电流淬灭后的电流密度强烈依赖于氩气密度。在实验中没有观察到这种趋势，这表明0 D动力学模型未捕获的效应-例如失控的种子运输-也很重要。
英文摘要：
Massive material injection has been proposed as a way to mitigate the formation of a beam of relativistic runaway electrons that may result from a disruption in tokamak plasmas. In this paper we analyse runaway generation observed in eleven ASDEX Upgrade discharges where disruption was triggered using massive gas injection. We present numerical simulations in scenarios characteristic of on-axis plasma conditions, constrained by experimental observations, using a description of the runaway dynamics with self-consistent electric field and temperature evolution in two-dimensional momentum space and zero-dimensional real space. We describe the evolution of the electron distribution function during the disruption, and show that the runaway seed generation is dominated by hot-tail in all of the simulated discharges. We reproduce the observed dependence of the current dissipation rate on the amount of injected argon during the runaway plateau phase. Our simulations also indicate that above a threshold amount of injected argon, the current density after the current quench depends strongly on the argon densities. This trend is not observed in the experiments, which suggests that effects not captured by 0D kinetic modeling -- such as runaway seed transport -- are also important.
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