X-Ray production and mitigation on the CTH experiment

The Compact Toroidal Hybrid experiment (CTH) at Auburn University has produced unexpectedly high X-Ray dosages in the surrounding facility. Two mechanisms for these emissions have been proposed: runaway electrons, driven by plasma current, and magnetic pumping. Here, we describe a measurement campaign where the X-Ray emissions are characterized by correlation experiments, using an X-Ray scintillator and a Geiger counter. A range of plasma conditions, involving various densities, rotational transforms, and accelerating potentials are produced, and the measured emission profiles are used to derive statistical distributions of X-Ray production. The observed energy, intensity, and spatial distributions of X-Rays are then correlated in time with the evolution of plasma conditions inside CTH, and are used to understand the X-Ray sources and develop mitigation strategies.