Runaway dynamics in reactor-scale spherical tokamak disruptions

Abstract

Understanding generation and mitigation of runaway electrons in disruptions is important for the safe operation of future tokamaks. In this paper we investigate runaway dynamics in reactor-scale spherical tokamaks. We study both the severity of runaway generation during unmitigated disruptions, as well as the effect that typical mitigation schemes based on massive material injection have on runaway production. The study is conducted using the numerical framework DREAM (Disruption Runaway Electron Analysis Model). We find that, in many cases, mitigation strategies are necessary to prevent the runaway current from reaching multi-megaampere levels. Our results indicate that with a suitably chosen deuterium-neon mixture for mitigation, it is possible to achieve a tolerable runaway current and ohmic current evolution. With such parameters, however, the majority of the thermal energy loss happens through radial transport rather than radiation, which poses a risk of unacceptable localised heat loads.

19 pages, 7 figures

References in corpus (6)

• DREAM: a fluid-kinetic framework for tokamak disruption runaway electron simulations
• Evaluation of the Dreicer runaway generation rate in the presence of high-Z impurities using a neural network
• Runaway electron deconfinement in SPARC and DIII-D by a passive 3D coil
• Effect of Two-Stage Shattered Pellet Injection on Tokamak Disruptions
• The hot-tail runaway seed landscape during the thermal quench in tokamaks
• Runaway dynamics in disruptions with current relaxation

Cited by in corpus (3)

• Fluid and kinetic studies of tokamak disruptions using Bayesian optimization
• Reduced kinetic modelling of shattered pellet injection in ASDEX Upgrade
• Runaway electron generation in disruptions mitigated by deuterium and noble gas injection in SPARC