GROUND SIMULATION OF SPACECRAFT CHARGING DISCHARGES

The search to control spacecraft-charging-induced discharges has been underway since the mid-seventies. Ground test simulations have been able to initiate discharges by irradiating typical exterior surface dielectrics, but not at the voltages predicted for space applications. In this paper, incident electron beam currents and voltages are analytically varied to evaluate discharges. A combination of lowand mid-energy electron beams indicate that the conditions necessary for discharges at surface voltage consistent with space flight predictions can be achieved. It has been found that a dual beam system operating at 12.5 and 32.5 KeV and using the space environment spectrum current density predicts discharges could occur at the experimentally measured electric field of 1 to 2 MV/cm. This field is in a bi-layer region just below the dielectric surface and the differential surface voltage is in the -1 to -2 KV range. The choice of the beam energy for the second source is critical.