Generation and Measurement of High Intermittent Heat Flux in GAMMA 10/PDX

Electron cyclotron heating (ECH) power modulation experiments have been conducted for GAMMA 10/PDX to generate and control the high heat flux and to develop an edge localized mode (ELM)-like intermittent heat load pattern for divertor simulation studies. Flux and energy spectra of end-loss electrons are measured using a multi-grid energy analyzer (loss electron diagnostics, LED). ECH-induced potential formation at plug regions (P-ECH) produces high-energy electron flows along the magnetic lines of force. The power scaling of electron flux in GAMMA 10/PDX indicates that higher ECH power generates higher electron flux. In this study,a new mirror antenna is developed to generate higher heat flux and concentrate the heating power on the axis. The energy density and heat flux obtained using previous systems are 0.06 MJ/m2 and 11.4 MW/m2, respectively,and those obtained using the new mirror systems are 0.09 MJ/m2 and 30 MW/m2, respectively. These values are still considerably lower than those of ITER ELM (mitigated ELMs in ITER is ∼0.5 MJ/m2 for t = 0.5 ms).