Curved Crystal Spectrometer with Position-Sensitive Solid-State Detector for Plasma Diagnostics

The characteristics of a Johann-type crystal spectrometer with a photodiode array (PDA) are described. The crystal used is LiF(200) with a bending radius of 100 cm, and the sensitivity of the PDA is measured for X-rays of 4 to 17 key. The collection efficiency η of charges created in the PDA is determined as a function of the X-ray energyE(keV): η=-0.026E+0.68. An asymmetrical spectral profile is observed when a monochromatic X-ray beam is incident on the PDA with an angle larger than 40°. The sensitivity of the spectrometer is also calibrated against a conventional X-ray tube. The PDA is used for the observation of X-ray lines from a high-temperature plasma in a vacuum spark. The resultant FeKα spectrum shows a spread over several channels due to blooming, when compared with that recorded on Kodak no-screen X-ray film.