New Soft x-ray PHA Diagnostic in the HT-7 Tokamak

A soft x-ray Pulse Height Analysis (PHA) diagnostic with the recently introduced Silicon Drift Detector (SDD) and a new MCA system has been installed in HT-7 for the measurements of electron temperature. With the SDD detector, the x-ray emission can be detected in the energy range from 1 kev up to 20 keV. The extremely low anode capacity of SDD allows very high counting rates of x-ray above 200 kHz and short shaping times below 0.25 μs to be measurede. In routine operation a counting rate of 120 kHz has been normally obtained with an energy resolution of better than 180 eV at 5.9 keV. The assembly is equipped with six SDD detectors measuring the soft x-ray emission integrated along six chords of the upper half plasma cross section. The preliminary results from the new soft x-ray PHA diagnostic are also presented in this paper.