Faraday-effect polarimeter diagnostic for internal magnetic field fluctuation measurements in DIII-D

Journal Article · Tue Nov 15 00:00:00 EST 2016 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4960056· OSTI ID:22596574

Ding, W. X.; Brower, D. L. ^[1]; Finkenthal, D. ^[2]; Muscatello, C.; Taussig, D.; Boivin, R. ^[3]

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1. Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)
2. Palomar Scientific Instruments, San Marcos, California 92069 (United States)
3. General Atomics, San Diego, California 92186 (United States)

Motivated by the need to measure fast equilibrium temporal dynamics, non-axisymmetric structures, and core magnetic fluctuations (coherent and broadband), a three-chord Faraday-effect polarimeter-interferometer system with fast time response and high phase resolution has recently been installed on the DIII-D tokamak. A novel detection scheme utilizing two probe beams and two detectors for each chord results in reduced phase noise and increased time response [δb ∼ 1G with up to 3 MHz bandwidth]. First measurement results were obtained during the recent DIII-D experimental campaign. Simultaneous Faraday and density measurements have been successfully demonstrated and high-frequency, up to 100 kHz, Faraday-effect perturbations have been observed. Preliminary comparisons with EFIT are used to validate diagnostic performance. Principle of the diagnostic and first experimental results is presented.

• OSTI ID: 22596574
• Journal Information: Review of Scientific Instruments, Vol. 87, Issue 11; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AXIAL SYMMETRY
BEAMS
COMPARATIVE EVALUATIONS
DENSITY
DETECTION
DIAGNOSIS
DISTURBANCES
DOUBLET-3 DEVICE
EQUILIBRIUM
FARADAY EFFECT
FLUCTUATIONS
INTERFEROMETERS
KHZ RANGE 01-100
MAGNETIC CORES
MAGNETIC FIELDS
NOISE
PERTURBATION THEORY
POLARIMETERS
PROBES
RESOLUTION