July 11, 2008
Evolving commercial and military requirements for high-frequency power amplification are driving the demand for modern vacuum electronics devices. The explosion of wideband RF communications, space-based communication, and geolocation, as well as advanced military radars and directed energy sources, are placing new requirements on the electron-beam current density, beam emittance, module size, lifetime, and efficiency of vacuum electronic devices. Novel techniques for constructing slow-wave structures and advanced electron collectors are addressing the latter requirements, but cathode technology has not kept pace. One of the more promising cathodes are scandates with reports of emission currents over 100 A/cm2. Unfortunately, there is very little understanding of the underlying physics and limited knowledge of the emitting species and re-supply of the scandate material therefore no clear path to optimizing this cathode’s operation. In this STTR program, Nanohmics and its University partner Ohio University, proposes to study the surface science of the scandate cathodes and use this information to optimize its emission performance and lifetime. These optimized cathodes will be tested in a TWT environment. This program will result in development of an optimized high current density commercial scandate cathode.
Development and optimization of a high current density, long lived, rugged cathode opens up applications in many areas. These include compact electron sources for klystrons, traveling wave tubes, and other RF- and microwave vacuum electronic devices as well as long life electron sources for X-ray tubes.