Investigation of RF Noise Generation from Space Vehicles

Analytical and experimental studies have been made on RF noise generated by two types of ion propulsion engines, namely the cesium contact ion engine and the Penning discharge engine. An analytical determination of noise generated by neutralized ion beams is made in which the following mechanisms are considered: electron-ion collisions, acceleration of electrons at the plasma boundary, ion-atom collisions, cathode shot noise, ion acceleration, black body radiation from ion emitter surface, and noise growth radiation. No noise was experimentally observed from the cesium contact engine over the frequency spectrum of 38 to 2200 Mc, but the Penning engine exhibited electron cyclotron radiation. Preliminary conclusions of this study are that reliable communications systems with a vehicle involving a Penning discharge propulsion engine should probably be operated above the cyclotron and plasma frequencies.