Ultrafast spectroscopy diagnostic to measure localized ion temperature and toroidal velocity fluctuations

Uzun Kaymak, İlker Ümit
McKee, G. R.
Schoenbeck, N.
Smith, D.
Winz, G.
Yan, Z.
A dual-channel high-efficiency, high-throughput custom spectroscopic system has been designed and implemented at DIII-D to measure localized ion thermal fluctuations associated with drift wave turbulence. A large-area prism-coupled transmission grating and high-throughput collection optics are employed to observe C VI emission centered near lambda = 529 nm. The diagnostic achieves 0.25 nm resolution over a 2.0 nm spectral band via eight discrete spectral channels. A turbulence-relevant time resolution of 1 mu s is achieved using cooled high-speed avalanche photodiodes and ultralow-noise preamplifiers. The system sensitivity is designed to provide measurements of normalized ion temperature fluctuations on the order of delta T-i/T-i <= 1%. (C) 2010 American Institute of Physics. [doi:10.1063/1.3479114]


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Wide-field turbulence imaging with beam emission spectroscopy
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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 asy...
Citation Formats
İ. Ü. Uzun Kaymak, G. R. McKee, N. Schoenbeck, D. Smith, G. Winz, and Z. Yan, “Ultrafast spectroscopy diagnostic to measure localized ion temperature and toroidal velocity fluctuations,” REVIEW OF SCIENTIFIC INSTRUMENTS, pp. 0–0, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/37992.