The hot-tail runaway seed landscape during the thermal quench in tokamaks

Abstract

Runaway electron populations seeded from the hot-tail generated by the rapid cooling in plasma-terminating disruptions are a serious concern for next-step tokamak devices such as ITER. Here, we present a comprehensive treatment of the thermal quench, including the superthermal electron dynamics, heat and particle transport, atomic physics, and radial losses due to magnetic perturbations: processes that are strongly linked and essential for the evaluation of the runaway seed in disruptions mitigated by material injection. We identify limits on the injected impurity density and magnetic perturbation level for which the runaway seed current is acceptable without excessive thermal energy being lost to the wall via particle impact. The consistent modelling of generation and losses shows that runaway beams tend to form near the edge of the plasma, where they could be deconfined via external perturbations.

6 pages, 3 figures

References in corpus (8)

• Radiation asymmetry and MHD destabilization during the thermal quench after impurity Shattered Pellet Injection
• Runaway dynamics in the DT phase of ITER operations in the presence of massive material injection
• Fast plasma dilution in ITER with pure Deuterium Shattered Pellet Injection
• Runaway Electron Seed Formation at Reactor-Relevant Temperature
• Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption
• Effects of magnetic perturbations and radiation on the runaway avalanche
• Assessing energy dependence of the transport of relativistic electrons in perturbed magnetic fields with orbit-following simulations
• Modelling of runaway electron dynamics during argon-induced disruptions in ASDEX Upgrade and JET

Cited by in corpus (9)

• Runaway electron deconfinement in SPARC and DIII-D by a passive 3D coil
• Effect of Two-Stage Shattered Pellet Injection on Tokamak Disruptions
• Confinement of passing and trapped runaway electrons in the simulation of an ITER current quench
• Bayesian optimization of massive material injection for disruption mitigation in tokamaks
• Runaway dynamics in disruptions with current relaxation
• Fluid and kinetic studies of tokamak disruptions using Bayesian optimization
• Runaway dynamics in reactor-scale spherical tokamak disruptions
• The impact of fusion-born alpha particles on runaway electron dynamics in ITER disruptions
• Modeling the complete prevention of disruption-generated runaway electron beam formation with a passive 3D coil in SPARC