Reservoir Scandate Cathode for Electric Propulsion

We propose to combine two revolutionary cathode technologies into a single device for use in electric space propulsion. This will overcome problems that both technologies have when operated alone. The cathode is currently the component which most limits performance and life in ion and Hall Effect thrusters. Improved cathodes are essential for NASA's next generation electric space propulsion initiative. The innovation will benefit both satellite and deep space missions. We have successfully demonstrated both stand-alone reservoir and scandate cathodes in hollow cathode geometries. Reservoir cathodes are known to provide unprecedented life and stability. Scandate cathodes dramatically lower operating temperature. By combining the two technologies, we incorporate extremely long life (greater than 10 years) and extremely low temperature (less than 850 degrees C) into a single device. The result will be a revolutionary enhancement in electric propulsion. Reservoir cathodes employ a chamber behind the emitter which contains a barium emissive material. This greatly increases the amount of barium available to the cathode. Scandate cathodes provide a scandium-containing cathode surface which lowers the work function.