Scale Effects on Ion Rocket Performance

Two geometrically similar sources, a 5- and a 20-cm dia. beam source, were scaled from a 10-cm dia. source to allow a performance comparison. The three ion sources are compared for ion chamber characteristies and over-all engine efficiency. The results of the chamber investigations are compared with scaling variations indicated by simple plasma theory. The effects of size on operating limits are also discussed. Mercury was used as the propellant.