Cathode for Electric Space Propulsion Utilizing Iodine as Propellant

A hollow reservoir cathode for use in ion and Hall thrusters which uses iodine as propellant. Reservoir cathodes have unique features not found in conventional impregnated cathodes. The critical barium reduction process occurs in the reservoir, not in the matrix, and this isolates that process from iodine poisoning. Also, the barium supply is 100 times greater than is available in conventional cathodes. This allows much higher rates of barium to flow to the cathode’s surface – enough to overcome iodine poisoning. Also, metals resistant to iodine attack can be used in the cathode matrix. We propose constructing large numbers of reservoir cathodes with various compositions and activities. We propose a systematic study of these cathodes in iodine to discover the factors which provide the successful performance. We also propose a miniature reservoir cathode for use in CubeSats, where iodine's compactness is most appealing. NASA is pursuing iodine EP because of its many advantages over xenon. These include low cost and high storage density.