A Critical History of Electric Propulsion: The First Fifty Years (1906-1956)

∗Chair of AIAA’s Electric Propulsion Technical Committee, 2002-2004. Associate Fellow AIAA. Chief Scientist at Princeton University’s Electric Propulsion and Plasma Dynamics Laboratory (EPPDyL). Associate Professor, Applied Physics Group, MAE Department. e-mail: [email protected]. †Presented at the 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Ft. Lauderdale, FL. Copyright c © 2004 by the author. Published by the AIAA with permission. Also published in the Journal of Propulsion and Power, Vol. 20, No. 2, pp. 193–203, MarchApril 2004. When writing history, it is tempting to identify thematic periods in the often continuous stream of events under review and label them as “eras”, or to point to certain achievements and call them “milestones”. Keeping in mind that such demarcations and designations inevitably entail some arbitrariness, we shall not resist this temptation. Indeed, the history of electric propulsion (EP), which now spans almost a full century, particularly lends itself to a subdivision that epitomizes the progress of the field from its start as the dream realm of a few visionaries, to its transformation into the concern of large corporations. We shall therefore idealize the continuous history of the field as a series of five essentially consecutive eras: