Development of a Two-Dimensional Thomson Scattering Diagnostic System involving Use of Multiple Reflection and the Time-of-Flight of Laser Light

Abstract

Two-Dimensional Thomson Scattering Measurement (2-D TS) was designed using multiple reflections and the time-of-flight of laser light. This new approach enable us to measure the r(radial)-z(axial) profiles of electron temperature and density. In this approach, (1) multiple reflections of YAG laser light are used to cover the whole r-z plane of the ST (Spherical Tokamak) plasma, and (2) the time delay of the scattered light along the laser beam is arbitrarily arranged by adjusting the multiply reflected laser light path in order to reduce the necessary number of detectors. Rayleigh scattering lights were observed successfully at two measurement points, suggesting that the basic principle of the 2-D Thomson scattering system functions effectively as a new extension of LIDAR (LIght Detection And Ranging) Thomson scattering system.

Design and development of a single-laser 2D Thomson scattering measurement system for TS-6 merging tokamak/magnetic reconnection experiments

“…Another cost-effective method is 2D measurement with the use of multiple reflections and time-of-flight (ToF) of laser light [4,5]. Laser light travels in the 2D plane, and scattered light pulses from multiple measuring points on different paths are guided into one polychromator with ToF delays.…”