Electron temperature measurement on QUEST spherical tokamak by thomson scattering system

Abstract

On QUEST, we are carrying out the steady state operation by RF current drive. A Thomson scattering (TS) system has been constructed to measure the plasma electron temperature. This system consists of a Nd:YAG laser of energy 1.65 J, a spherical mirror for collection of the scattering light, and a polychromator for spectroscopy. Because the Thomson scattering signal is weak for the low-density RF-sustained plasma, many scattering pulse signals were accumulated from steady-state plasmas. Electron temperature profiles were obtained for the steadystate spherical tokamak (ST) plasma for the first time. Six spatial points were measured by moving the fiber position, and the plasma electron temperature was in the range 10-500 eV. © 2013 The Japan Society of Plasma Science and Nuclear Fusion Research.