Fast Soft X-ray Images of MHD Phenomena in NSTX
Authors: C.E. Bush, B.C. Stratton, J. Robinson, L.E. Zakharov, E. D. Fredrickson, D. Stutman, K. Tritz
Abstract:
A variety of MHD phenomena have been observed on NSTX. Many of these affect fast particle losses, which are of major concern for future burning plasma experiments. Usual diagnostics for studying these phenomena are arrays of Mirnov coils for magnetic oscillations and PIN diode arrays for soft x-ray emission from the plasma core. Data reported here are from an unique fast soft x-ray imaging camera (FSXIC) with a wide-angle (pinhole) tangential view of the entire plasma minor cross section. The camera provides a 64x64 pixel image, on a CCD chip, of light resulting from conversion of soft x-rays incident on a phosphor to the visible. We have acquired plasma images at frame rates of 1-500 kHz (300 frames/shot), and have observed a variety of MHD phenomena: disruptions, sawteeth, fishbones, tearing modes, and ELMs. New data including modes with frequency > 90 kHz are also presented. Data analysis and modeling techniques used to interpret the FSXIC data are described and compared, and FSXIC results are compared to Mirnov and PIN diode array results.
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Presented at: 17th Topical Conference on High Temperature Plasma Diagnostics, Albuquerque, NM (May 2008)
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Download PPPL-4339 (pdf 6.56MB 16pp)
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