EFFECTS OF PLASMA FLOW ON ELECTROSTATIC DISTURBANCES IN A Q MACHINE.

The evolution of a large discontinuity in density in a single‐ended Q machine has been found to be adequately described by a free‐streaming model of the ions modified by a density gradient electric field due to a finite electron temperature. As the electron temperature is increased through microwave heating at cyclotron resonance, the profile of the discontinuity is found to broaden spatially as predicted by the theoretical model. The plasma ion drift velocity along the magnetic field can be measured from the motion of the discontinuity and is found to be in close agreement with the drift velocity measured from the propagation of small‐amplitude ion‐acoustic waves. An estimate of the ion thermal velocity parallel to the magnetic field can also be obtained from the broadening of th discontinuity profile. The ion drift velocity exhibits systematic variation with changes in oven and ionizer temperatures which is attributable to the electron‐ion balance in the region surrounding the hot ionizer.