Effects of Helium massive gas injection level on disruption mitigation on EAST

TL;DR

This paper uses NIMROD simulations to study how varying helium gas injection levels affect disruption mitigation in the EAST tokamak, revealing different plasma cooling behaviors and disruption types based on impurity amounts.

Contribution

It provides new insights into the impact of helium injection levels on plasma cooling and disruption dynamics in EAST, highlighting critical thresholds for different disruption scenarios.

Findings

Above a critical impurity level, a single MHD activity causes complete core temperature collapse.

Below the critical level, multiple minor disruptions occur before thermal quench.

Different cooling scenarios (complete and partial) depend on impurity injection amount.

Abstract

In this study, NIMROD simulations are performed to investigate the effects of massive helium gas injection level on the induced disruption on EAST tokamak. It is demonstrated in simulations that two different scenarios of plasma cooling (complete cooling and partial cooling) take place for different amounts of injected impurities. For the impurity injection above a critical level, a single MHD activity is able to induce a complete core temperature collapse. For impurity injection below the critical level, a series of multiple minor disruptions occur before the complete thermal quench (TQ).