Stabilization of a Neutral-Beam—Sustained, Mirror-Confined Plasma

We report results of plasma confinement experiments with an auxiliary warm-plasma component flowing along magnetic field lines to suppress ion-cyclotron instabilities. The reduced plasma losses, with the lower fluctuation amplitude, permits neutral-beam build-up of a 13-keV deuterium plasma to densities as high as 4 \ifmmode\times\else\texttimes\fi{} ${10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ corresponding to peak beta values of 0.4. Variation of the beam energy demonstrates that longer confinement times are achieved at higher ion energies.