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

Large-orbit, nonthermal d/sup +/ migma plasma with P/sub theta/approx.0 and E/sub ion/ = 0.7 MeV was formed in the center of a simple mirror with densities n = 10/sup 9/--10/sup 10/ cm/sup -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 E/sub i/n/sub c/tauapprox.10/sup 14/ keV cm/sup -3/ s, n/sub c/tauapprox.10/sup 11/ cm/sup -3/ s, luminosity approx.10/sup 29/ cm/sup -2/ s/sup -1/.