Plasma and Fusion Research

Volume 13, 3402047 (2018)

Regular Articles

Application of He I Line Intensity Ratio Method to Tokamak Plasma in TOKASTAR-2
Ryoma YOKOYAMA, Atsushi OKAMOTO, Takaaki FUJITA, Hideki ARIMOTO, Masato MINOURA, Kohei YASUDA and Takahiro YAMAUCHI
Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
(Received 28 December 2017 / Accepted 19 March 2018 / Published 22 May 2018)


Temporal evolution of electron density and temperature in TOKASTAR-2 tokamak plasma is obtained for the first time by He I line intensity ratio method. In the calculation of collisional radiative model, we consider the effect of radiation trapping and validity of quasi-steady-state approximation for metastable states. He I line intensities are measured using a monochromator that has a photomultiplier tube as a detector. To evaluate line intensity ratios used for analysis, their sensitivity factors for plasma parameters are newly introduced. We investigate plasma current Ip dependence of the electron density ne and temperature Te by changing the charging voltage of ohmic heating VOH. The ne depended on Ip independent of VOH. The Spitzer resistance obtained from the measured Te was consistent with the plasma resistance at Ip top phase.


TOKASTAR-2, He I line intensity ratio method, CR model, radiation trapping, tokamak plasma

DOI: 10.1585/pfr.13.3402047


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