Preparations and Plans for Runaway Electron Mitigation Coil (REMC) Studies on HBT-EP

A Runaway Electron Mitigation Coil (REMC) is an optimally shaped 3D conducting element inside of the vacuum vessel that is driven by the disruption voltage to provide a "fail-safe" prevention of high-energy runaway electrons [1]. This poster presents preparations and plans to install a REMC in HBT-EP. Scoping studies show a wide range of coil positions yield significant coupling of the pre-disruption plasma current to the passive coil, exceeding the coupling expected in DIII-D [2] and SPARC [3]. The flexibility of the HBT-EP device simplifies installation and will enable extensive model validation, including coupling changes from modifying the plasma major radius. REMC studies will explore interactions between the passive coil system and plasma operation. Disruption forces, measured with piezoelectric strain gauges and load cells, and the role of halo currents will be documented. Preparations for REMC studies also include scoping experiments conducted on both regular and "slide-away" discharges. Large non-axisymmetric fields from existing control coils will also be configured to resemble the REMC fields and triggered to study mode locking, disruption effects, and plasma motion monitored by fast videography, hard X-ray detectors, EUV sensors, halo current detectors, and Mirnov coils.

[1] Allen H Boozer 2011 Plasma Phys. Control. Fusion 53 084002.

[2] D.B. Weisberg et al 2021 Nucl. Fusion 61 106033.

[3] R.A. Tinguely et al 2021 Nucl. Fusion 61 124003.