Reflectometer density fluctuation measurements on DIII‐D

An O‐mode, homodyne reflectometer system utilizing seven discrete channels spanning 15–75 GHz is in operation on DIII‐D. A frequency‐tunable X‐mode system is also used to take fluctuation data from reflecting layers lying between those of the fixed frequency, O‐mode system. In order to demonstrate t...

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Bibliographic Details
Published in:Review of Scientific Instruments 1990-10, Vol.61 (10), p.3016-3018
Main Authors: Doyle, E. J., Lehecka, T., Luhmann, N. C., Peebles, W. A., Philipona, R., Burrell, K. H., Groebner, R. J., Matsumoto, H., Osborne, T. H.
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102 - Fusion Energy- Plasma Research- Diagnostics
CLOSED PLASMA DEVICES
DOUBLET-3 DEVICE
ENERGY-LEVEL TRANSITIONS
Exact sciences and technology
FLUCTUATIONS
INELASTIC SCATTERING
OPTICAL EQUIPMENT
Physics
Physics of gases, plasmas and electric discharges
Physics of plasmas and electric discharges
PLASMA DENSITY
PLASMA DIAGNOSTICS
SCATTERING
THERMONUCLEAR DEVICES
THOMSON SCATTERING
TOKAMAK DEVICES
VARIATIONS
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Summary:An O‐mode, homodyne reflectometer system utilizing seven discrete channels spanning 15–75 GHz is in operation on DIII‐D. A frequency‐tunable X‐mode system is also used to take fluctuation data from reflecting layers lying between those of the fixed frequency, O‐mode system. In order to demonstrate the power and flexibility of this diagnostic, results are presented from several different plasma regimes, including L to H transitions, ELMS, and high beta operation. One specific example is that at all L–H transitions, high‐frequency (≥50 kHz) fluctuations are dramatically suppressed in a localized region near the edge of the plasma on a timescale of ≊100 μs.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.1141973