中国聚变工程试验堆装置在电流猝灭过程中逃逸电流产生和抑制的数值模拟

中国聚变工程试验堆等离子体电流高达14 MA,等离子体破裂将产生大量逃逸电子,形成巨大的逃逸电流,如不抑制将对装置造成极大的损伤。本文利用托卡马克等离子体破裂的零维模型,数值计算了中国聚变工程试验堆在电流猝灭阶段Dreicer机制产生逃逸种子的雪崩倍增,获得了逃逸电流和逃逸动能随时间的演化关系,并与解析结果进行了对比。研究了影响电子雪崩过程逃逸电流的关键物理因素,发现破裂后等离子体电子温度、密度和有效电荷对逃逸种子电流的产生和逃逸电流的抑制有巨大影响。通过增加电子密度,从而增强碰撞耗散,可以有效抑制破裂后逃逸电流,这对选择合适的方法抑制破裂后的逃逸电子具有积极的意义。

Numerical Simulation of Runaway Current Generation and Suppression During Current Quenching in CFETR Device

The plasma current of the China Fusion Engineering Test Reactor (CFETR) is as high as 14 MA, and the plasma disruption will produce a large number of runaway electrons, forming a huge runaway current, which will cause great damage to the device if not suppressed. In this paper, using the zero dimensional model of tokamak plasma disruption, the avalanche multiplication of runaway seeds produced by the Dreicer mechanism in the current quenching phase of the CFETR device is numerically calculated, and the evolution relationship between the runaway current and the runaway kinetic energy with time is obtained, which is compared with the analytical results. The key physical factors that affect the runaway current in the electron avalanche process are studied. It is found that the electron temperature, density and effective ion charge after disruption have a great influence on the generation of runaway current seed and the suppression of runaway current. By increasing electron density and hence enhancing collisional dissipation, the runaway current after disruption can be effectively suppressed, which is of positive significance for selecting appropriate methods to suppress runaway electrons during disruption.