Demonstration of improvement in the signal-to-noise ratio of Thomson scattering signal obtained by using a multi-pass optical cavity on the Tokyo Spherical Tokamak-2

H Togashi; A Ejiri; J Hiratsuka; K Nakamura; Y Takase; T Yamaguchi; H Furui; K Imamura; T Inada; H Kakuda; A Nakanishi; T Oosako; T Shinya; M Sonehara; S Tsuda; N Tsujii; T Wakatsuki; M Hasegawa; Y Nagashima; K Narihara; I Yamada; H Tojo

doi:10.1063/1.4891707

Demonstration of improvement in the signal-to-noise ratio of Thomson scattering signal obtained by using a multi-pass optical cavity on the Tokyo Spherical Tokamak-2

Rev Sci Instrum. 2014 Nov;85(11):11D846. doi: 10.1063/1.4891707.

Authors

H Togashi¹, A Ejiri¹, J Hiratsuka², K Nakamura¹, Y Takase¹, T Yamaguchi¹, H Furui¹, K Imamura¹, T Inada¹, H Kakuda², A Nakanishi¹, T Oosako¹, T Shinya¹, M Sonehara², S Tsuda¹, N Tsujii¹, T Wakatsuki², M Hasegawa³, Y Nagashima³, K Narihara³, I Yamada⁴, H Tojo⁵

Affiliations

¹ Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan.
² Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.
³ Research Institute of Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan.
⁴ National Institute for Fusion Science, Toki 509-5292, Japan.
⁵ Japan Atomic Energy Agency, Naka 311-0193, Japan.

PMID: 25430259
DOI: 10.1063/1.4891707

Abstract

The multi-pass Thomson scattering (TS) scheme enables obtaining many photons by accumulating multiple TS signals. The signal-to-noise ratio (SNR) depends on the accumulation number. In this study, we performed multi-pass TS measurements for ohmically heated plasmas, and the relationship between SNR and the accumulation number was investigated. As a result, improvement of SNR in this experiment indicated similar tendency to that calculated for the background noise dominant situation.