Development of Thomson Scattering System in GAMMA 10

Thomson scattering (TS) is one of the most reliable diagnostics to measure the electron temperature and electron density radial profiles in fusion plasmas. In GAMMA 10, a yttrium-aluminum-garnet (YAG)-TS system was constructed with the large solid angle of TS collection optics. We carried out Rayleigh and Raman scattering experiments for system settings and density calibration. We applied the YAG-TS system to the GAMMA 10 plasma. We can successfully measure the radial profiles of electron temperature and density in the central cell of GAMMA 10 by using the YAG-TS system in a single plasma shot. Moreover, in order to increase the TS signal intensities, we have constructed a multipass TS system of the polarization-based system with image relaying optics. Clear TS signals from first to fourth passing lasers through the GAMMA 10 plasma were obtained. The obtained TS signal intensity was about three times larger by first to fourth passing lasers through the plasma than that of the first pass.