Numerical studies of the imaging properties of doubly focussing crystals and their application to ITER

Abstract

Line brightness calculations for the parameters at the International Thermonuclear Experimental Reactor (ITER) and results from recent experiments on the Tokamak Fusion Test Reactor (TFTR) indicate that time-resolved measurements of the central ion temperature and other central plasma parameters should be feasible on ITER with nonperturbing amounts of krypton. Since the measurements will have to be performed in the presence of high fluxes of 14-MeV neutrons from DT-fusion reactions, the size of windows, apertures and x-ray detectors must be as small as possible. Under these conditions, the use of doubly focussing crystals can significantly enhance the signal-to-noise ratio. This paper describes numerical studies of the focussing properties of spherically bent crystals and their application to ITER.