Performance Calculations for the ITER Core Imaging X-Ray Spectrometer (CIXS)*

The US is providing a 1D imaging x-ray crystal spectrometer system as a primary diagnostic for measuring profiles of ion temperature (T$_{\mathrm{i}})$ and toroidal flow velocity (v) in the ITER plasma core (r/a $=$ 0-0.85). The diagnostic must provide high spectral resolution (E/$\Delta $E \textgreater\ 5,000), spatial resolution of 10 cm, and time resolution of 10-100 ms, and must operate and survive in an environment having high neutron and gamma-ray fluxes. This work presents spectral simulations and tomographic inversions for obtaining local T$_{\mathrm{i}}$ and v, comparisons of the expected count rate profiles to the requirements, the degradation of performance due to the nuclear radiation background, and measurements of the rejection of nuclear background by detector pulse-height discrimination.