An original calibration technique for soft x-ray detectors and its use in the Tore Supra tomographic system

This paper describes in detail the recent progresses which have been made in Tore Supra for developing a new technique of calibration of the soft x-ray (SXR) detectors in the range 1-30 keV. The diode response as a function of the flux of photons resulted accurately linear over almost three orders of magnitude. Apart from a limited number of deficient detectors, promptly replaced with new ones, the spread of the diode responses (84 detectors) is about 20% total of the average value. It allowed the derivation of the calibration factor for each detector of the tomography system. The effect of the environmental temperature, in the range 15 degrees-40 degrees, has also been studied, revealing that up to 35 degrees the linearity of diode response and these calibration factors remain constant. It demonstrates the capability of discriminating slight and localized changes in the two dimensional spatial distribution of the SXR intensity.