Plasma and Fusion Research

Volume 16, 2401042 (2021)

Regular Articles

Radial Profile Estimation of Electron Density in a Linear Plasma Device NUMBER Using a Single Line-of-Sight Signal
Minami SUGIMOTO, Atsushi OKAMOTO, Takaaki FUJITA, Hideki ARIMOTO, Shunya HIGUCHI and Konan YAGASAKI
Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
(Received 30 November 2020 / Accepted 12 January 2021 / Published 21 April 2021)

Abstract

In this paper, a method for estimating the radial profile of electron density ne using a single line-of-sight signal by the He I line intensity ratio method is proposed. By applying this method to cylindrical helium plasma, in which electron temperature was almost uniform and density was uniform in the center, we tried to estimate the parameters representing spatial distribution. It was confirmed that a good distribution estimation result could be obtained by considering the sensitivity factor, the rate at which the line intensity ratio changes as the parameters change, during optimization. Two methods of considering a sensitivity factor are proposed: using the best combination of intensity ratios for analysis in terms of the sensitivity factor, and weighting the objective function using the sensitivity factor. The former method can be analyzed in short computational time, although its applicability is limited. The latter method can be used when it is not obvious which set of intensity ratios is best to use, although it takes more computational time compared with the former method. Both methods reproduce the parameter of a radial density profile.

Keywords

He I line intensity ratio, collisional radiative model, spatial distribution estimation, linear plasma device, parameter optimization

DOI: 10.1585/pfr.16.2401042

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