When intense beams of 10- to 40-keV electrons are injected into the auroral zone ionosphere, a large suprathermal electron flux of up to 1013 electrons (cm2 s sr keV)-1 greater than 10 eV energy appears in the regionof space surrounding the beam-injecting vehicle. The intensity of these electrons increases with altitude and can be quenched by the release of neutral gas. These electrons when measured aboard the beam-emitting payload are undoubtedly related to the neutralization of this payload. The neutralizing electron current forms a discharge around the accelerator payload during beam emission as measured by photometers. The suprathermal electrons are probably produced by collective plasma effects in this neutralization process. Suprathermal electrons are also observed when relatively low electron beam fluxes reflected from the atmosphere below the rocket pass near the payload after the electron accelerator has been

turned off. These electrons are apparently produced by a beam-plasma interaction. The process of electron beam injection accelerates ions observed on the beam-emitting vehicle with a spectrum extending to a broad peak at about 0.5 keV seen only in the direction perpendicular to B. The exact nature of the acceleration process is not known. In the thermal ion region (few eV) during beam injection, sporadic fluxes similar to ambient intensities are observed, but immediately after gun turn-off, only a greatly depleted portion of the spectrum remains. The thermal ions' recovery only after several seconds indicates a space charge region up to 1 km in radius. Evidence that ions could play a major role in the plasma processes accompanying beam injection is presented. Oscillations at or near heavy ion gyroperiods are seen in the payload neutralization current, in the luminous sheath surrounding the payload, and in the intensity of 0.5-keV

suprathermal electrons. The oscillating electron intensities are apparently responsible for the luminous oscillations, and both phenomena are out of phase with the return current which flows radially inward to the vehicle. This may represent an oscillating sheath in which the ions gyrate in phase inward and outward in a purely radial mode. It is speculated that ion interactions might be responsible for partially quenching an intense plasma discharge at each accelerator turn-on. An attempt is made in this paper to draw a parallel between some of the above mentioned beam injection effects and similar observations relating to natural auroral plasmas.