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Fast-ion D -alpha diagnostic for NSTX

  • Author(s): Heidbrink, WW
  • Bell, RE
  • Luo, Y
  • Solomon, W
  • et al.

Published Web Location Commons 'BY' version 4.0 license

A fast-ion D -alpha (FIDA) diagnostic is under development for the National Spherical Torus Experiment (NSTX). The FIDA technique is a charge-exchange recombination spectroscopy measurement that exploits the large Doppler shift of Balmer-alpha light from energetic hydrogenic atoms to infer the fast-ion density. The principal objective of the NSTX installation is to measure the transport of beam ions caused by fast-ion driven instabilities; detection of perpendicular acceleration of fast ions during high harmonic fast wave heating is another important goal. Recent data from a DIII-D FIDA diagnostic guide the design. The planned NSTX diagnostic consists of two separate instruments focusing on different aspects of the measurement. One instrument uses a transmission grating spectrometer to measure the perpendicular energy spectrum and the spatial profile every 10 ms; the anticipated resolution is ∼10 keV in energy and ∼5 cm in radius. A second instrument employs bandpass filters to detect fast-ion redistribution events with millisecond temporal resolution. © 2006 American Institute of Physics.

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