Experimental study of the toroidal distribution of energetic electron loss in the presence of a Runaway Electron Mitigation Coil (REMC)

The Runaway Electron Mitigation Coil (REMC) concept first proposed in [1] utilizes a passive, toroidally non-axisymmetric wire that couples to the plasma current during disruptions via the induced loop voltage. The coil’s magnetic fields break the flux surfaces throughout the plasma, helping to inhibit the production and avalanche of runaway electrons. Following the first-ever installation of an REMC, this poster presents studies of the Hard X-Ray (HXR) signal generated by runaway electrons on the HBT-EP tokamak. The runaway electrons generated during low-density plasma operation produce HXRs when they collide with plasma-facing material. HXR detectors have been previously utilized to observe the loss of energetic electrons in HBT-EP, and will be located at anticipated impact regions to measure the spatial emission distribution of HXRs with and without an REMC. We plan to present the differences in HXR signals between three different cases: normal plasma disruptions, disruptions where the high-field side REMC is activated, and disruptions where the low-field side REMC is activated. Cases where the coil is externally driven by a high-power amplifier during plasma operation (i.e. before the current quench) will also be discussed.

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