2XIIB plasma confinement experiments

This paper report results of 2XIIB neutral-beam injection experiments with plasma-stream stabilization. The plasma stream is provided either by a pulsed plasma generator located on the field lines outside the plasma region or by ionization of neutral gas introduced at the mirror throat. In the latter case, the gas is ionized by the normal particle flux through the magnetic mirror. A method of plasma start-up and sustenance in a steady-state magnetic field is reported in which the plasma stream from the pulsed plasma generator serves as the initial target for the neutral beams. After an energetic plasma of sufficient density is established, the plasma generator stream is replaced by the gas-fed stream. Life-times of the stabilized plasma increase with plasma temperature in agreement with the plasma stabilization of the drift-cyclotron loss-cone mode. The following plasma parameters are attained by using the pulsed plasma generator for stabilization: n approximately 5X1013cm-3, Wsub(i) approximately 13keV, Tsub(e)=85eV, and ntausub(p) approximately 7X1010cm-3s. With the gas feed, the mean deuterium ion energy is 9keV and the peak density n approximately 1014cm-3. In the latter case, the energy confinement parameter reaches ntausub(E)=6.2X1010cm-3s, and the particle confinement parameter reaches ntausub(p)=1.2X1011cm-3s. (author)