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Title: High-frequency fluctuation measurements by far-infrared laser Faraday-effect polarimetry-interferometry and forward scattering system on MST

Magnetic fluctuation-induced transport driven by global tearing modes has been measured by Faraday-effect polarimetry and interferometry (phase measurements) in the MST reversed field pinch. However, the role of small-scale broadband magnetic and density turbulence in transport remains unknown. In order to investigate broadband magnetic turbulence, we plan to upgrade the existing detector system by using planar-diode fundamental waveguide mixers optimized for high sensitivity. Initial tests indicate these mixers have ×10 sensitivity improvement compared to currently employed corner-cube Schottky-diode mixers and ×5 lower noise. Compact mixer design will allow us to resolve the wavenumbers up to k ∼ 1–2 cm{sup −1} for beam width w = 1.5 cm and 15 cm{sup −1} for beam width w = 2 mm. The system can also be used to measure the scattered signal (amplitude measurement) induced by both plasma density and magnetic fluctuations.
Authors:
; ;  [1] ;  [2]
  1. Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA 90095 (United States)
  2. Department of Physics, University of Wisconsin-Madison, Wisconsin 53706 (United States)
Publication Date:
OSTI Identifier:
22303827
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; BEAM PROFILES; FAR INFRARED RADIATION; FARADAY EFFECT; FLUCTUATIONS; INTERFEROMETRY; LASERS; PLASMA DENSITY; POLARIMETRY; REVERSED-FIELD PINCH DEVICES; SCATTERING; SCHOTTKY BARRIER DIODES; SENSITIVITY; TEARING INSTABILITY