Wide-field turbulence imaging with beam emission spectroscopy

McKee G. R., Fonck R. J., Shafer M. W., Uzun-Kaymak I. U., Yan Z.

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: 10.1063/1.3495788
  • Journal Name: REVIEW OF SCIENTIFIC INSTRUMENTS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Middle East Technical University Affiliated: Yes

Abstract

Imaging of the size, shape, time-averaged, and time-resolved dynamics of long-wavelength density turbulence structures is accomplished with an expanded, high-sensitivity, wide-field beam emission spectroscopy (BES) diagnostic on DIII-D. A 64-channel BES system is configured with an 8 X 8 grid of discrete channels that image an approximately 7 X 9 cm region at the outboard midplane. The grid covers multiple correlation lengths and each channel shape matches the measured radial-poloidal correlation length asymmetry of turbulent eddies. The wide field 8 X 8 imaging capability allows for sampling of essentially the full two-dimensional spatial correlation function for typical plasma conditions. The sampled area can be radially scanned over 0.4 < r/a < 1, including the core ((n) over tilde /n < 1% ), pedestal, and scrape-off-layer. The resulting time-resolved visualizations of turbulence and flows provide critical data on turbulence dynamics. (C) 2010 American Institute of Physics. [doi:10.1063/1.3495788]