Development of 2-D Thomson Scattering Measurement Using Multiple Reflection and the Time-of-Flight of Laser Light

A new two-dimensional Thomson scattering measurement (2-D TS) system has been developed using multiple reflections and time-of-flight (TOF) of laser light. Its new ideas of our 2-D TS system are (1) to reflect YAG laser light for multiple times to cover the whole r - z plane of the ST (Spherical Tokamak) plasma, and (2) to reduce the number of polychromators and detectors using the time delay of the scattered light along the laser beam. We measured for the first time, Rayleigh scattering light signals with 50 ns time difference from two measurement points using a single detector, demonstrating the basic principle of the 2-D Thomson scattering system.