Polarization-Controlled Multi-Pass Thomson Scattering System in the Tandem Mirror GAMMA 10

An effective method to increase Thomson scattering (TS) signals is required in low-density plasmas. Multi-pass TS has the advantage of enhancing scattered signals. We constructed a double-pass TS system for a polarization-based system modelled on the GAMMA 10 TS system. In the second step, we have developed the multi-pass TS system based on the former double-pass TS system. In order to evaluate the effectiveness of the polarization-based configuration, the multi-pass system was installed in the GAMMA 10 TS system, which is capable of multi-pass scattering. We undertook Rayleigh scattering experiments. The integrated scattering signal was magnified to be approximately three times as large by using the multi-pass system with 6 passes.