ARTIFICIAL ELECTRON AND ION-BEAM EFFECTS - ACTIVE PLASMA-EXPERIMENT

The Active Plasma Experiment uses intensive electron beam emission for the study of dynamic processes in the magnetosphere and upper ionosph ere. The beam energy and current are as high as 8 keV and 100 mA and t he pitch angle of the emission varies in the range from 50 degrees to 80 degrees. The basic cycle of electron injection is formed by current pulses of different duration, intensity, and frequency. The spacecraf t potential is balanced by a low-energy xenon plasma generator during the electron beam injection. The spacecraft potential is measured by t he floating probe, and the response of the environment is studied by t he charged particle spectrometer working in the energy range from 0.05 to 25 keV. During the neutral or ionized Xe release without the elect ron gun operation the spacecraft potential remains nearly unchanged an d the observed energy spectra of charged particles do not exhibit the presence of any acceleration process. The spacecraft potential during electron beam emission does not exceed 50 V if the Xe plasma or the ne utral gas was released together with the electrons. The electron gun f iring creates a disturbance which produces a broad spectrum of energet ic electrons extending up to 1.5 keV. The acceleration process can be explained by the introduction of the electric field with intensity of about 100 V/m. This intensity is in agreement with the observed ExB dr ift velocity. The spatial extent of the disturbance is established to be tens of meters.