The Electric Potential of a Spacecraft Injecting an Electron Beam into the Earth's Ionosphere

The problem of the electric potential value for the spacecraft injecting an electron beam into the Earth's ionosphere is considered. The formulas defining the spacecraft's electric potential in the equilibrium state as a function of experimental parameters are derived. It is shown that the presented theoretical results are in a good agreement with both the results of numerical modeling and experimental data. A comparison of different models of spacecraft charge neutralization is performed. An explanation is given for the facts related to the difficulties of interpretation of the mechanisms of spacecraft charge neutralization within a period less than the time of ionization of neutral particles and plasma heating by the injected beam.