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Plasma rotation measurements in NCSX using x-ray spectroscopy

This research forum paper discusses the use of high-resolution X-ray spectroscopy to measure plasma rotation in the NCSX tokamak. It explores the importance of studying rotation, the potential for installing X-ray spectroscopy, and the benefits of adding stellarator information to the rotation database. The paper also presents the use of H- and He-like argon and neon to measure core and edge rotation profiles.

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Plasma rotation measurements in NCSX using x-ray spectroscopy

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  1. Plasma rotation measurements in NCSX using x-ray spectroscopy R. Granetz and J. Rice NCSX research forum 7-8 Dec 2006

  2. Why are we interested in doing this? • Crucial test of QAS: Rotation is a relatively simple thing to measure (as compared to confinement), and therefore should be studied as soon as possible in FY11. • Don’t have to wait for DNB/CHERS; High-resolution x-ray spectroscopy should be easy to install, although spatial resolution will not be as good as CHERS. • Plasmas might even rotate without NBI • Add stellarator information to tokamak rotation database, hopefully improving our understanding of momentum physics.

  3. Scaling of intrinsic rotation from multiple tokamaks suggests scaling to ITER

  4. Current PPPL/C-Mod collaboration on X-ray spectroscopy • Core: • H & He-like argon (using curved crystal and 2-D detector) to measure Ti and Vi in core – M. Bitter, K. Hill, J. Rice, A. Ince-Cushman • Edge: • He-like neon (Ti and Vi in outer radii of plasma) – M. Bitter, J. Rice, A. Ince-Cushman

  5. X-ray sensitive CCD Crystal Chamber NESOXS • NEon SOft X-ray Spectrometer • Spatially resolving spherically bent high resolution spectrometer looking at He-like Neon in the pedestal region of the plasma. • Provides impurity poloidal rotation profiles for 0.8 < r/a <0.95

  6. He-like Crystal B-port H-like Crystal He-like Detectors H-like Detector HIREX SR • HIgh REsolution X-ray spectrometer - Spatially Resolving • Spatially resolving spherically bent crystal spectrometer looking at H & He-like Argon • Provides impurity temperature and rotation profiles for r/a < 0.8

  7. Some details • The new 2-D HIREX on C-Mod replaces 5 single-chord HIREX systems. One or more of these single-chord systems could be installed on NCSX (core rotation). Should be relatively inexpensive to do this. Might also be possible to duplicate the 2-D HIREX system (more expensive option). • Might also be possible to duplicate the NESOX system (edge rotation) • Would need: • to puff small amounts of argon into plasma • Te ~ 1-2+ keV • A pair of toroidally-opposing views would avoid the necessity of an absolute wavelength calibration

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