Pertinent space charge equations and numerical values are presented for application of electron beams to achieve high specific impulses for rocket propulsion. A chart is derived for space charge limited mass flow where the ratio of molecular weight to number of electronic charges is plotted against accelerating voltage at 1-cm fixed spacing. The Pierce gun J. R. Pierce Theory and Design of Electron Beams, Van Nostrand, 1949, Chapter 10 is cited as possible of modification for application of the calculations. Effective currentcarrying area would be 2 to 5 of total surface. With 30,000v the area would be 2 to 5 sq mkg of thrust. Rocket electrical neutrality might be attained by having half the emitted particles postively charged and half negatively.