Millimeter-wave backscatter diagnostic for the study of short scale length plasma fluctuations (invited)

Journal Article · Sun Oct 15 00:00:00 EDT 2006 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.2235874· OSTI ID:20861288

Rhodes, T L; Peebles, W A; Nguyen, X; VanZeeland, M A; De Grassie, J S; Doyle, E J; Wang, G; Zeng, L ^[1]

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1. Electrical Engineering Department, University of California, Los Angeles, Los Angeles, California and Physics Department, University of California, Los Angeles, Los Angeles, California (United States)

The development, laboratory tests, and experimental results relating to a new high-k diagnostic technique for the study of short scale length turbulence are reported. The system is based on backscattering of a millimeter-wave (94 GHz) probe beam by density fluctuations within the plasma. This diagnostic has been fully integrated with an upgraded far-infrared forward scattering system on the DIII-D tokamak. The combined system monitors a broad turbulent spectral range from 0 to 40 cm{sup -1}. Short-scale (e.g., electron temperature gradient scale) modes as well as longer wavelength (e.g., ion temperature gradient and trapped electron mode scale) instabilities are simultaneously monitored to accurately characterize plasma turbulence. The backscattering geometry and innovative use of the second harmonic electron cyclotron resonance as an internal 'beam dump' allow detection of small level fluctuations at high k, while maximizing discrimination against the ubiquitous, larger level, low-k fluctuations.

• OSTI ID: 20861288
• Journal Information: Review of Scientific Instruments, Vol. 77, Issue 10; Other Information: DOI: 10.1063/1.2235874; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BACKSCATTERING
DIAGNOSTIC TECHNIQUES
DOUBLET-3 DEVICE
ELECTRON CYCLOTRON-RESONANCE
ELECTRON TEMPERATURE
FLUCTUATIONS
GHZ RANGE 01-100
ION TEMPERATURE
MONITORS
PLASMA
PLASMA CONFINEMENT
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA INSTABILITY
TEMPERATURE GRADIENTS
TRAPPED ELECTRONS
TURBULENCE