Development of a soft X-ray pulse height analyzer on the J-TEXT tokamak

A soft X-ray pulse height analyzer has been designed and installed on the J-TEXT tokamak for measuring the electron temperature and possibly for monitoring the impurity content and concentration. A multi-channel analyzer, a set of amplifiers, and three silicon drift detectors constitute the detection system. An off-line analysis code was developed to analyze the raw data recorded by the system. The system can measure a minimum electron temperature of 400 eV, and its routine operation provides electron temperature measurements at three different positions with a temporal resolution of 60 ms and channel separation of 18 cm. Line radiation from some moderate and high Z impurities are observable by the system. The results show that the intensity of line radiation from heavy impurity ions is inversely proportional to the plasma density under similar discharge conditions.