Application of a PILATUS II Detector to an X-Ray Imaging Crystal Spectrometer for fast Measurement of Ti and Rotation-Velocity Profiles on Alcator C-Mod*

A high resolution imaging x-ray crystal spectrometer (XICS) is being developed for Doppler measurement of radial profiles of ion temperature, T$_{i}$, and rotation velocity on Alcator C-mod. The XICS consists of a spherically bent crystal and a 2D imaging x-ray detector, and provides x-ray spectra from highly charged ions from multiple plasma sightlines. The proof of principle of the XICS was demonstrated by measurement of Ar XVII K$\alpha $ spectral images from +/- 8 cm of the plasma height in Alcator C-Mod and +/- 40 cm in NSTX. However, the time resolution was limited to values $>$100 ms by the $\sim $400 kHz global count-rate limit of the available 2D gas detector. A silicon pixel array detector, PILATUS II, with a count-rate capability of 1 MHz PER PIXEL, was tested on C-Mod by recording spectra of ArXVII at 3.1 keV, and should enable XICS time resolution $<$ 10 ms. The detector test results and C-Mod XICS design and expected performance will be presented.