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

Abstract

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 the three parallel laser beams formed by multiple reflections. New ideas are: (1) a YAG laser beam is reflected by 6 mirrors so that covers the whole r-z plane of the Spherical Tokamak (ST) plasma; (2) the observation position is determined by the time delay on the scattered light which helps to largely reduces the necessary numbers of spectrometers and detectors. Using a torus plasma merging device TS-4. we successfully measured the electron temperature at nine points with showing the basic theory of this novel TS system.