Shuttle charging by tether controlled electron beam

During the reflight of the tethered satellite system, the electron generator assembly (EGA) emitted steady electron beams six times with the satellite deployed between 6.2 and 16.1 km. Maximum beam energies and currents were 1.65 keV and 0.4 A, respectively. Data presented here show that: (1) emissions create local electron clouds that can charge the shuttle, (2) ionization of thruster gas by beam electrons in the sheath did not reduce the shuttle potential, (3) the EGA utilizes more than half the induced potential, and (4) ionospheric density gradients and magnetic field orientations affect the circuit's potential distribution.