Basic Study of Two-Dimensional Thomson Scattering Measurement by Multiple Reflections and Time-of-Flight of Laser Beam

• Published in: Electronics and communications in Japan Vol. 97; no. 3; pp. 1 - 7
• Main Authors: Ito, Shingo, Sakamoto, Hisashi, Kotani, Raita, Inomoto, Michiaki, Ono, Yasushi, Narihara, Kazumichi
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01.03.2014
• Subjects: 2-D measurement; Beams (radiation); electron temperature/density measurements; Laser beams; Merging; multiple reflections of laser light; Raman scattering; Reflection; Semiconductor lasers; Thomson scattering; time-of-flight; Tokamak devices; Two dimensional
• ISSN: 1942-9533; 1942-9541
• DOI: 10.1002/ecj.11519

SUMMARY A novel two‐dimensional Thomson scattering (TS) measurement system has been developed by adopting the time‐of‐flight (TOF) difference in the signals scattered from three parallel laser beams formed by multiple reflections. New ideas are: (1) a YAG laser beam is reflected by 6 mirrors so that it covers the whole r–z plane of a spherical Tokamak (ST) plasma; (2) the observation position is determined by the time delay of the scattered light, which helps to significantly reduce the necessary numbers of spectrometers and detectors. Using a TS‐4 torus plasma merging device. we successfully measured the electron temperature at nine points, demonstrating the basic theory of this novel TS system.