Saturation curves of low-voltage ionization chamber for ITER at 10–30 keV

A low voltage ionization chamber (LVIC) is a very promising alternative to ITER X-ray detectors owing to its outstanding radiation tolerance. To investigate the characteristics of the LVIC preliminary prototype and evaluate its application in ITER, the saturation curves corresponding to 10–30 keV monochromatic radiations were measured in the Shanghai Synchrotron Radiation Facility. In the saturation region, the output current variation was linear with respect to input power, indicating that the LVIC can be used to detect X-ray emissions. Based on the saturation curves and related simulation, it is speculated that the saturation voltages needed for LVICs of the external and internal cameras in ITER might be no greater than 150 V and 300 V respectively. Responsivity (R) derived from experimental results was compared with theoretical calculations, showing good agreement at 15–20 keV, but significant deviations at 10 keV and 30 keV, which will be studied in the future. It is estimated that R of the LVIC ranges from 2.66 × 10−2 to 1.89 × 10−3 A/W between 10 to 30 keV. The experimental results show promising potential for LVIC application in ITER as an X-ray detector.