Journal Article Simulations of runaway electron generation including the hot-tail effect

Nuga, H.  ,  Yagi, M.  ,  Fukuyama, A.

57 ( 8 )  , pp.086011-1 - 086011-9 , 2017-06 , IOPScience
The hot-tail (H-T) effect in disruption of impurity injections is considered. The contribution of the H-T effect to runaway electron (RE) current, which arises from fast thermal quenching, is studied using a two-dimensional Fokker–Planck simulation. It is found that in a high-density plasma the total RE current is reduced owing to the high collisionality. We also found that if the thermal quench is fast enough to invoke the H-T effect, the effect produces more seed REs than when the H-T effect is excluded even in high-density plasmas. In the high-density region (ne ∼ 1021 m−3) with fast thermal quenching, nevertheless the increment of the seed REs due to the H-T effect is generally small (tens of milliamperes) while the increment of the total RE current reached 2 MA owing to the avalanche effect.

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