PPPL-4394

A Spatially Resolving X-ray Crystal Spectrometer for Measurement of Ion-temperature and Rotation-velocity Profiles on the AlcatorC-Mod Tokamak

Authors: K.W. Hill, M. L. Bitter, S.D. Scott, A. Ince-Cushman, M. Reinke, J.E. Rice, P. Beiersdorfer, M.-F. Gu, S.G. Lee, Ch. Broennimann, and E.F. Eikenberry

Abstract:
A new spatially resolving x-ray crystal spectrometer capable of measuring continuous spatial profiles of high resolution spectra (λ/dλ > 6000) of He-like and H-like Ar Kα lines with good spatial (~1 cm) and temporal (~10 ms) resolutions has been installed on the Alcator C-Mod tokamak. Two spherically bent crystals image the spectra onto four two-dimensional Pilatus II pixel detectors. Tomographic inversion enables inference of local line emissivity, ion temperature (Ti), and toroidal plasma rotation velocity (vφ) from the line Doppler widths and shifts. The data analysis techniques, (Ti) and vφ profiles, analysis of fusion-neutron background, and predictions of performance on other tokamaks, including ITER, will be presented.
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Submitted to:Review of Scientific Instruments (May 2008)

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