Overview of the beam emission spectroscopy diagnostic system on the National Spherical Torus Experiment

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Smith D. R., Feder H., Feder R., Fonck R. J., Labik G., McKee G. R., ...More

REVIEW OF SCIENTIFIC INSTRUMENTS, vol.81, no.10, 2010 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 81 Issue: 10
  • Publication Date: 2010
  • Doi Number: 10.1063/1.3478660
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Middle East Technical University Affiliated: Yes


A beam emission spectroscopy (BES) system has been installed on the National Spherical Torus Experiment (NSTX) to study ion gyroscale fluctuations. The BES system measures D-alpha emission from a deuterium neutral heating beam. The system includes two optical views centered at r/a approximate to 0.45 and 0.85 and aligned to magnetic field pitch angles at the neutral beam. f/1.5 collection optics produce 2-3 cm spot sizes at the neutral beam. The initial channel layout includes radial arrays, poloidal arrays, and two-dimensional grids. Radial arrays provide coverage from r/a approximate to 0.1 to beyond the last-closed flux surface. Photodetectors and digital filters provide high-sensitivity, low-noise measurements at frequencies of up to 1 MHz. The BES system will be a valuable tool for investigating ion gyroscale turbulence and Alfven/energetic particle modes on NSTX. (C) 2010 American Institute of Physics. [doi:10.1063/1.3478660]