High-Power Plasma Switch for 11.4 GHZ Microwave Pulse Compressor

65072 The Environmental Protection Agency (EPA) recently classified beryllia (BeO) as a hazardous material because of its toxicity, and manufacturers are discontinuing the production of products that contain BeO due to potential liability problems. As an alternative, aluminum nitride (AIN) based materials are being developed for medium-to-high power vacuum electron devices; however, a lack of suitable hermetic metallization technologies hampers their insertion into vacuum electron devices, such as microwave tubes operating at cryogenic temperatures. This project will develop hermetic refractory metallization and associated brazing technologies so that AIN composites can be attached to copper members for microwave tube applications. Phase I will investigate molybdenum thick-film metallization, associated nickel-plating, and brazing techniques to attach newly developed AIN composites to copper members. Adhesion between the metallization and AIN composites will be measured, and the hermeticity of the brazed joints will be evaluated. Commercial Applications and Other Benefits as described by the awardee: Almost every medium-to-high vacuum electron device would benefit from new hermetic, refractory metallization that is compatible with high thermal conductivity aluminum nitride composites. Applications include klystrons and gyrotrons to supply microwave energy in chemical processes, materials processing, direct broadcast satellites, magnetic fusion, and microwave communications.