Effects of the REMC and RMPs on the toroidal distribution and energy characteristics of hard X-rays on the HBT-EP tokamak

Runaway electron (RE) mitigation stands as a challenge to high current tokamaks because they can incur significant damage to the vessel wall and plasma-facing components if electron beams are able to form. This poster presents progress on characterizing the energy spectrum and toroidal distribution of energetic electron deconfinement on HBT-EP under the effects of non-axisymmetric magnetic perturbations, specifically through the activation of an runaway electron mitigation coil (REMC) and resonant magnetic perturbations (RMPs). The REMC offers a potential solution to the RE problem by deconfining REs through a perturbation generated by inductive coupling to a disrupting plasma [1]. A fully-passive REMC has been installed on the HBT-EP tokamak, which triggers on plasma disruptions using analog circuitry. RMPs have also been used to study energetic electron deconfinement [2-4], and external m/n = 3/1 RMPs have been previously shown to have an effect on the toroidal distribution of deconfined electrons on HBT-EP. The energetic electron distribution is determined through the energy spectrum of hard x-rays (HXRs) detected outside the vacuum vessel. Using metallic filters, the time-resolved energy spectrum of HXR emission is determined.

[1] A. Boozer. 2011 Plasma Phys. Control. Fusion 53.

[2] N. Commaux et al 2011 Nucl. Fusion 51.

[3] M. Gobbin et al 2018 Plasma Phys. Control. Fusion 60.

[4] M. Lehnen et al 2008 Phys. Rev. Letters 255003.