Oxide cathodes produced by plasma deposition

Summary form only given. The best oxide cathodes have been capable of long life and high-current-density. The problem has been the ability to consistently reach maximum performance. The complex chemistry of the deposition and activation process have made consistent performance unrealizable. SLAC, UCD, and LBL are developing a plasma deposition process that eliminates the problems with binders, carbonate reduction, peeling, and porosity. The emission layer is deposited using plasma deposition of metallic barium in vacuum with an oxygen background gas. An applied bias voltage drives the oxide plasma into the nickel surface. Since the oxide is deposited directly, it does not have problems with poisoning from hydrocarbon binder. The density of the oxide layer is increased from the 40% to 50% for standard oxide cathodes to nearly 100% for plasma deposition. It is expected that the repeatable process, increased density, and elimination of poisoning agents will provide a long-life, high-current-density cathode for a variety of applications.