Electron Density Measurement by Using a Multi-Channel Interferometer System in the Tandem Mirror GAMMA 10

Fluctuation in the plasma is important to be measured for studying the improvement of the plasma confinement by the formation of the plasma confinement potential. Density fluctuation is observed using microwaves, such as interferometer, reflectometry and Fraunhofer diffraction method. We have constructed a new multi-channel microwave interferometer for measuring the plasma density and fluctuation radial profiles in a single plasma shot. In order to study higher density plasma operation, we have started sub-millimeter hydrogen ice pellet injection experiments into the potential confined plasma. We successfully measured the time dependent density and line-integrated density fluctuation radial profiles in the pellet injection experiments using the multi-channel microwave interferometer.