1. Presented as Preprint 64-704 at the AIAA Fourth Electric Propulsion Conference, Philadelphia, Pa., August 31-September2,1964; revision received December 10, 1964. This work was supported by NASA on Contract NAS3-2594.
2. Kash, S. W., Plasma Acceleration (Stanford University Press, Stanford, Calif. 1960), pp.79-88.