Thomson scattering measurements in low-density plasmas in the TST-2 spherical tokamak

H. Togashi, A. Ejiri, H. Homma, T. Shinya, Y. Takase, K. Toida, N. Tsujii, T. Yamaguchi, Y. Yoshida, H. Furui, M. Sonehara, K. Nakamura, W. Takahashi, T. Takeuchi, S. Yajima, H. Yamazaki, M. Hasegawa, Y. Nagashima, H. Tojo

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Abstract

Thomson scattering (TS) diagnostics have been widely used in fusion studies to measure profiles of electron temperature Te and electron density ne. In order to measure the low-density plasmas (ne ≤ 1018 m-3) in TST-2, which is sustained by lower hybrid wave power, the signal-to-noise ratio in TS measurement has been improved by various means. For instance, optimization of the detecting system, accumulation of TS data obtained from reproducible discharges, and application of a coaxial multi-pass scheme were carried out. As a result, the profiles have been measured successfully and a peaked ne profile and a hollow Te profile were obtained. Additionally, isotropy of Te near the plasma center was confirmed by coaxial double-pass TS measurement.

Original languageEnglish
Article numberC12020
JournalJournal of Instrumentation
Volume10
Issue number12
DOIs
Publication statusPublished - Dec 18 2015

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All Science Journal Classification (ASJC) codes

  • Mathematical Physics
  • Instrumentation

Cite this

Togashi, H., Ejiri, A., Homma, H., Shinya, T., Takase, Y., Toida, K., ... Tojo, H. (2015). Thomson scattering measurements in low-density plasmas in the TST-2 spherical tokamak. Journal of Instrumentation, 10(12), [C12020]. https://doi.org/10.1088/1748-0221/10/12/C12020