Measurement of radial profile of the x-ray emission on the JFT-2M tokamak

Temporal and spatial profiles of the x-ray spectra in the range 3--400 keV have been measured for divertor plasmas on the JFT-2M tokamak with a recently developed pulse-height analyzer system. This detection system incorporates an array of six vertically placed sets of a high-purity germanium spectrometer. Each x-ray energy spectrum can be measured simultaneously with a sampling interval of 1--255 ms. Dynamic change of the electron temperature profile, such as time behavior with H-mode transition, can be measured with this system. It was observed that the electron temperature profile became broad just after the H-mode transition during neutral-beam heated discharge. In the lower-hybrid current drive experiments, the x-ray emission profile depended strongly on the density. The x-ray intensity from the peripheral region became strong with increase in electron density