Experiment with stored 0.7-MeV ions: Observation of stability properties of a nonthermal plasma

Large-orbit, nonthermal ${\mathrm{d}}^{+}$ migma plasma with ${\mathrm{P}}_{\mathrm{\theta }}$∼0 and ${\mathrm{E}}_{\mathrm{ion}=0.7\mathrm{}}$ MeV was formed in the center of a simple mirror with densities n${=10\mathrm{}}^9$–${10}^{10}$ ${\mathrm{cm}}^{\mathrm{-}3}$. Confinement time was 20–45 s. Flute, negative-mass, and ion-cyclotron instabilities, found in other mirrors at several orders-of-magnitude lower n, were not observed. An instability was suppressed by an electric field. Confinement parameters are ${\mathrm{E}}_{\mathrm{i}}$ ${\mathrm{n}}_{\mathrm{c}}$τ∼${10}^{14}$ keV ${\mathrm{cm}}^{\mathrm{-}3}$ s, ${\mathrm{n}}_{\mathrm{c}}$τ∼${10}^{11}$ ${\mathrm{cm}}^{\mathrm{-}3}$ s, luminosity ∼${10}^{29}$ ${\mathrm{cm}}^{\mathrm{-}2}$ ${\mathrm{s}}^{\mathrm{-}1}$.