著者

Yuya KAWAMATA Akira EJIRI Kyohei MATSUZAKI Yuichi TAKASE Naoto TSUJII Takumi ONCHI Yoshihiko NAGASHIMA

出版者

The Japan Society of Plasma Science and Nuclear Fusion Research

雑誌

Plasma and Fusion Research (ISSN:18806821)

巻号頁・発行日

vol.14, pp.1402072, 2019-04-11 (Released:2019-05-22)

参考文献数

9

被引用文献数

2

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The stray light is a major problem in Thomson scattering (TS) measurements. The main cause of stray light is unnecessary divergence of the incident laser beam and an aperture is a standard component to reduce it. In order to improve the aperture configuration (including size, number and position in the laser injection tube), a peripheral beam profile monitor, consisting of a screen with a through hole for the laser beam and a CMOS camera, was developed. Instead of the actual laser injection tube a mock-up tube was used to measure the peripheral beam profiles under various aperture configurations. The configuration with four 15mm diameter apertures was chosen and installed on the TS system for the TST-2 spherical tokamak. The stray light was reduced to about 4% compared to the smaller diameter injection tube with no apertures. As a result, it became possible to make TS measurements in the electron density range above 1.0 × 1017 m−3.