Preliminary results of density turbulence measurements using fast sweep reflectometry in DIII-D
POSTER
Abstract
Recently, the capability of the state-of-the-art density profile reflectometer on DIII-D has been expanded to determine the radial profile of electron density fluctuations. Measurement of reflectometer phase fluctuations (f ≤ ~5 MHz) associated with O-mode launch during fast RF frequency sweep operation, has allowed both the wavenumber spectrum and radial profile of ne fluctuations to be analytically derived. The analyzed radial wavenumber range is from ~1.2 cm-1 to ~10 cm-1, which is limited by Bragg scattering condition. Preliminary results show that L-mode turbulence levels are small (δn/n ~ 1%) in the core (ρ < 0.6) when the normalized ne and Te gradients are small. However, as the gradients steadily increase with radius (ρ > 0.6), turbulence levels also steadily increase. The comparison with ne fluctuation measurements such as BES and DBS in various plasma conditions will be presented. Further investigation of this analysis will be also presented.
Presenters
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Lei Zeng
UCLA, University of California, Los Angeles, University of California Los Angeles
Authors
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Lei Zeng
UCLA, University of California, Los Angeles, University of California Los Angeles
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William A Peebles
University of California, Los Angeles
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Terry L Rhodes
University of California, Los Angeles
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Neal A Crocker
UCLA, University of California, Los Angeles
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Rongjie Hong
Oak Ridge Assoc Univ, UCLA, University of California, Los Angeles
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George R McKee
University of Wisconsin - Madison, University of Wisconsin, Madison