Faraday-effect polarimetry for current profile measurement in the tokamak plasma edge

Chen, J.; Brower, D. L.; Benedett, T.

doi:10.1063/5.0101550

Title: Faraday-effect polarimetry for current profile measurement in the tokamak plasma edge

Journal Article · 19 August 2022 · Review of Scientific Instruments

DOI: https://doi.org/10.1063/5.0101550 · OSTI ID:1895596

^[1]; Brower, D. L. ^[2];

^[2]

Univ. of California, Los Angeles, CA (United States); General Atomics
Univ. of California, Los Angeles, CA (United States)

Toroidal current profile measurements in the tokamak plasma edge are critical for fusion plasma physics research and model validation. A three-wave Faraday-effect polarimeter-interferometer with a sub-centimeter spatial resolution is proposed on the DIII-D tokamak to determine the edge current profile via Abel inversion. By using probe beams with 316 µm wavelength, a low-field-side, vertical-view, single-pass optical layout covering the plasma edge region (R = 2.15–2.27 m) is assessed. Measurements with no greater than 0.1° polarimetric systematic uncertainty, no greater than 0.01° polarimetric root-mean-square noise (1 kHz bandwidth), and a 0.8 cm radial chord spacing are considered feasible based on the achieved performance of existing systems using similar wavelengths on fusion devices. Furthermore, synthetic diagnostic calculations taking various factors into account, such as diagnostic uncertainty and quality of magnetic flux surfaces, find that the edge current profile can be determined with up to 0.12 MA/m² uncertainty, or about 10% of the peak current density in the pedestal of an investigated high-confinement plasma.

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Research Organization:: General Atomics, San Diego, CA (United States)

Sponsoring Organization:: USDOE Office of Science (SC) Fusion Energy Sciences (FES)

Grant/Contract Number:: FC02-04ER54698; SC0019004

OSTI ID:: 1895596

Journal Information:: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 8 Vol. 93; ISSN 0034-6748

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY
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Title: Faraday-effect polarimetry for current profile measurement in the tokamak plasma edge

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