Bolometer Measurements of the Radiated Power and Estimates of the Effective Ion Charge Z on the Keda Torus Experiment

We have measured the power radiated by the plasma in the Keda Torus eXperiment (KTX) using a 20-channel AXUV bolometer. The bolometer has a frequency response bandwidth of 40 kHz, spatial resolution better than 40 mm, and overlap between adjacent channels of about 20%. For an ultra-low q discharge, the radiated power obtained from the bolometer measurements is about 8.0% of the ohmic heating input power. In addition, together with the H-alpha-emission data, we have used the bolometer data to calculate the effective ion charge Z(eff) profile, which proves to agree well with a plasma-resistivity calculation and which is hollow in the central region of a poloidal cross-section of the KTX.