Novel, Reliable, and Cost-Effective Input Coupler for High RF Power Applications

Input couplers capable of carrying high RF power to superconducting accelerating cavities, such as those used in nuclear physics research, are not only expensive but also difficult to process and condition up to their extremely high operating power and field gradient. Particular problems include: (1) secondary electron multipacting, which limits coupler performance; and (2) the need for metal surfaces to be super-clean of contaminants and have very low gas desorption rates. This project will utilize design for manufacturing (DFM) principles that, if applied early in the design phase, could significantly reduce overall costs. The Phase I feasibility study showed that DFM principles could be applied to the coupler design with a unique modular sub-assembly to allow for RF conditioning of major components individually. Increased cost effectiveness along with reduced multipacting and out-gasing was demonstrated. In Phase II, the prototype coupler will be developed, fabricated, and tested for large applications. Three new coating materials and methods, novel joining technology, and multipacting reducing methods will be experimentally investigated