Measurement of Flow Velocity of MPD Arcjet in GAMMA 10

At both end cells of GAMMA 10, two of Magneto-Plasma-Dynamic Arcjet (MPDA) are installed. MPDAs consists of two coaxial electrodes (tungsten stick and molybdic cylinder), and can produce quasi-stationary hydrogen plasmas. In GAMMA 10, the plasma generated by the MPDAs are used as the seed plasma. The main plasma is produced by ion cyclotron range of frequency (ICRF) waves in combination with the hydrogen gas injection. In the center at r=0 near the mirror throat of plug/barrier cell, the flow velocity and the mach number are measured with a mach probe in cases of several discharge voltages. The flow velocity and the mach number increase with the discharge voltage. The mach number of the seed plasma and the main plasma (from the confined region) is also measured in the radial direction. The flow velocity and the mach number of the seed plasma become small in the core region than in the peripheral region.