Modification of spacecraft charging and the near-plasma environment caused by the interaction of an artificial electron beam with the earth's upper atmosphere

The Beam-Atmosphere Interaction (BAI) involves the ionization created in the earth's upper atmosphere by electron beams emitted from a low altitude spacecraft. This process is described by two coupled non-linear differential electron transport equations for the up-going (along magnetic field line) and down-going differential energy flux. The equations are solved numerically,using the MSIS atmospheric model and the IRI ionospheric model, yielding estimates of the differential electron energy flux density at the spacecraft location. At altitudes below 200-250 km and forbeam energies around 1 keV, it is shown that secondary electrons supply a significant contribution to the return current to the spacecraft and thereby reduce the spacecraft potential. Our numerical results are in good agreement with observations from the CHARGE-2 sounding rocket experiment.A more detailed study of the BAI as it relates the CHARGE-2 observations are found in [Neubert et al., 1990].