Fundamental studies of rapid plasma heating by collective interactions, using strong turbulence and relativistic electron beams. Annual progress report, April 1, 1973--March 31, 1974

The experiments all involved rapid heating of a magnetically confined collisionless plasma column with a high-current relativistic electron beam (RE B). An impontant feature, which differentiates these experiments from sorne others, is that the fully ionized plasma column was injected through a 5-cm orifice along magnetic lines into a hard vacuum in a 40-cm-diameter chamber, eliminating the effects of walls and neutral gas around the column. Thus the electron beam did not create plasma, but only- interacted with the already-existing, finite column. Three distinct plasma conditions were usedi (a) injected plasma having a temperature of tens of electron volts and density between 10/sup 13/ and 6 x 10/ sup 13/ cm/s up -3/; (b) injected plasma heated to several keV by turbulent heating; and (c) highly turbulent plasma (electrostatic instabilities generated during turbulent heating). The strongest REB interaction was with plasma condition (c). Plasma heating to as much as 15 keV per electron-ion pair was achieved. The ion energy distribution was enhanced at high energies, with the ions containing 1/3 to 1/4 of the total plasma energy. The plasma was stable after heating. (auth