Fluctuation in the plasma needs to be measured for studying the improvement of the plasma confinement by the formation of the plasma confinement potential. A newly constructed multichannel microwave interferometer and ultrashort-pulse reflectometry were used for measuring the line integrated plasma density profile and density fluctuation profile in a few plasma shots. The first results of density and density fluctuation measurements in the central cell of the tandem mirror GAMMA 10 are described by using the multi-channel interferometer and ultrashort-pulse reflectometry.