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

摘要

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.