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

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. (C) 2014 AIP Publishing LLC.