Convex crystal x-ray spectrometer for laser plasma experiments

Measuring time and space-resolved spectra is important for understanding Hohlraum and Halfraum plasmas. Experiments at the OMEGA laser have used the Nova TSPEC which was not optimized for the OMEGA diagnostic space envelope or for the needed spectroscopic coverage and resolution. An improved multipurpose spectrometer snout, the MSPEC, has been constructed and fielded on OMEGA. The MSPEC provides the maximal internal volume for mounting crystals without any beam interferences at either 2× or 3× magnification. The RAP crystal is in a convex mounting geometry bent to a 20 cm radius of curvature. The spectral resolution, E/dE, is about 200 at 2.5 keV. The spectral coverage is 2 to 4.5 keV. The MSPEC can record four separate spectra on the framing camera at time intervals of up to several ns. The spectrometer design and initial field-test performance will be presented and compared to that of the TSPEC.