Reservoir Scandate Cathode for Electric Propulsion

Mars and lunar cargo missions would benefit, as would the upcoming JUNO mission to Jupiter. Also, piloted interplanetary mission become feasible with sufficient cathode output and life. Earth transfer, station-keeping and earth-escape should occur by all-electric means. It would lower cost, size, mass, and complexity. This technology would also help NASA's conventional cathode applications. Improved cathodes are needed for microwave amplifiers for space communications. The cathode is the performance-limiting component in these devices. A higher output cathode is especially needed for terahertz amplifiers and sources. The so-called "terahertz gap" is a vast region of frequency space that is unutilized, largely because of cathode technology limitations. Scandate cathodes are the key to accessing that space. In short, NASA needs higher bit rates, more power, and higher frequency for space communications and a host of other applications, and these are largely limited by the cathode.

All the applications described in NASA commercial applications apply to non-NASA markets except interplanetary space travel. More powerful thrusters are needed in commercial satellites for orbital transfer. These would allow all-electric propulsion for larger, heavier satellites operating in geo-synchronous orbits. All-electric propulsion lowers mass and size and raises efficiency. Other areas include Department of Defense radars and communications. This is the largest market for high-performance cathodes. The cathodes proposed here would increase life, performance, frequency data rates and resolution in these systems. Nongovernmental applications lie in high-speed x-ray tomography, electron beam-stimulated lasers, especially at UV, and commercial geo-synchronous satellite downlinks and propulsion. Hollow cathodes can be used as a source of high current density electrons for applications such as electron beam welding or as a source of electrons in corrosive environments. The cathodes proposed here are capable of creating electron beams of 1000 amps/cm2 or more. Even though the energy spread is high, the extraordinary current densities make for an extremely bright beam. More »