Far-forward collective scattering measurements of density fluctuations in the helically symmetric experiment stellarator

Journal Article · Fri Oct 15 04:00:00 EDT 2010 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3464471· OSTI ID:22055774

Deng, C B; Brower, D L ^[1]

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1. Department of Physics, University of California, Los Angeles, California 90095 (United States)

The multichannel interferometer system on the helically symmetric experiment (HSX) stellarator is reconfigured to perform far-forward collective scattering measurements of electron density fluctuations. The collective scattering system has nine viewing chords with 1.5 cm spacing. Scattered power is measured using a homodyne detection scheme. Far-forward collective scattering provides a line-integrated measurement of fluctuations within the divergence of the probe beam covering wavenumber range: k{sub perpendicular}<2 cm{sup -1}. The perpendicular wavenumber consists of poloidal and radial contributions that vary with chord position. Both coherent modes and broadband fluctuation are measured. When HSX is operated without quasihelical symmetry at B{sub T}=1 T and n{sub e}{approx}4x10{sup 12} cm{sup -3}, a coherent electrostatic fluctuation is observed.

• OSTI ID: 22055774
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 81; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAMS
DENSITY
DETECTION
ELECTRON DENSITY
FLUCTUATIONS
HSX STELLARATOR
INTERFEROMETERS
SCATTERING
SYMMETRY