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Fast Signal Modeling for Thomson Scattering Diagnostics and Effects on Electron Temperature Evaluation

Hisamichi FUNABA, Ichihiro YAMADA, Ryo YASUHARA, Hiyori UEHARA, Hiroshi TOJO¹⁾, Eiichi YATSUKA¹⁾, Jong-ha LEE²⁾ and Yuan HUANG³⁾

National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292, Japan

1)

National Institutes for Quantum Science and Technology, Naka, Ibaraki 311-0193, Japan

2)

Korea Institute of Fusion Energy, Daejeon 34133, Korea

3)

Southwestern Institute of Physics, P. O. Box 432, Chengdu 610041, China

(Received 27 December 2021 / Accepted 21 February 2022 / Published 18 May 2022)

Abstract

As a signal processing method for fast digitizers of the switched-capacitor-type in Thomson scattering diagnostics, a “model fitting” method is proposed. An ideal shape of the signal is estimated by this method by averaging many Thomson scattering signals. After applying this method to a relatively low density LHD plasma, the scattering of electron temperature profiles becomes small. The magnitude of error is also reduced by about 60% at some spatial channels in the core plasma. Simulations of signals with some noises based on the JT-60SA Thomson scattering system enables a showing of the expected error in electron temperature. The error can be suppressed by the “model fitting” method.

Copyright (c) 2022 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

Thomson scattering, electron temperature, signal processing

DOI: 10.1585/pfr.17.2402032

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