A miniature filamentless X-ray tube for the on-board calibration of space-borne X-ray detectors

The on-orbit calibration of the space X-ray detectors is important to obtain the accurate science data. Radioactive isotopes such as 241Am and 55Fe are generally used to implement calibration for space X-ray mission. However, the radioactive source is potential risk for the health safety and also causes a persistent radiation background during X-ray detector operation in space. On-orbit calibration of X-ray detectors has always been a difficult problem for space missions. This paper presents a miniature filamentless X-ray tube (MFXT) with tungsten target which can be used to calibrate X-ray detector on-orbit. At −12 kV high-voltage applied on MFXT, the strong L-series of characteristic X-ray of tungsten target is produced, so the gain and offset parameters of detector can be easily determined by the energy peaks of characteristic X-rays of tungsten. And after about 24 h of cumulative experiment, at least two characteristic ray peaks that can be used for calibration are formed with 5 minutes cumulative time after turning on it again with 5.2E+3 counts/s/sr radiation intensity by MFXT. As of the miniature, low power consumption and high reliability, this MFXT is an alternative to replace the radioactive source for on-orbit detector calibration in space missions.