X-Ray Observations and Electron Temperature Measurement by Soft X-Ray Spectroscopy on the CTH Experiment

Hard x-ray (HXR) emission of runaway electrons with energies up to a few MeV are observed in the Compact Toroidal Hybrid (CTH) torsatron experiment (R = 0 . 75 m , a ~ 0 . 2 m , B <= 0 . 7 T , n_e <=10¹⁹m^-3 , I_p <= 65 kA). HXRs were measured using a scintillator approximately 4 m from the CTH device oriented tangentially to the plasma current. A sudden absence of HXRs before and during abruptions in the plasma current was observed. Electron temperature measurements are derived from soft x-ray measurements using an Amptek spectrometer. The soft x-ray spectrometer views the Bremsstrahlung emission along a single chord through the plasma in the energy range from 0 . 7 - 4 keV . Central temperature measurements will be presented.

This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610