Double-crystal x-ray spectroscopy at JET

Abstract
A double‐crystal monochromator has been brought into operation at JET to measure absolute wavelengths and intensities of impurity spectral lines in the soft x‐ray region from about 0.1 to 2.3 nm. It is capable of operating also during the deuterium‐tritium (active) phase of JET because its detector is very effectively shielded against neutrons and hard x rays. The spectrometer has been swept over a wide wavelength range, around characteristic line groups as well as monochromatic line scans.