Amount:$500,000

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. 

Commercial Applications and Other Benefits as described by the awardee: Cost effective RF coupler designs will be required worldwide for many DOE projects such as the TESLA, SNS, RIA, the future Muon project, and the Jefferson Laboratory upgrade project.  Also, the technologies developed in this project (including super-clean vacuum surfaces, new coating materials and methods, and joining of dissimilar materials) should have applications in industries where high voltage gradients in vacuums are required (e.g.,  microwave tube, accelerator, and high vacuum industries).