ILC Coupler Design

Superconducting radio frequency (SRF) power couplers are used to introduce RF power into evacuated accelerating cavities typically operating at a few degrees Kelvin. These couplers are historically a problematic component that adversely affects the cost and reliability of the entire accelerator system. This project will develop a coupler which is low in capital and operating cost, highly reliable, and efficient. The coupler design is intended to have application to a wide variety of Super Conducting Radio Frequency Accelerators, such as Free Electron Lasers, Energy Recovery Linear Accelerators, as well as the International Linear Collider. Cost drivers considered in the design include fabrication costs as well as handling and processing requirements during assembly of the couplers. All known coupler operational limitations have been addressed and eliminated in the design, including vacuum thermal radio frequency breakdown, and catastrophic failure. During the Phase I project simulations were performed to optimize the radio frequency design for a highly efficient power coupler. Low power models were built and tested to verify the design simulations. Additionally, material properties and surface treatments for reducing radio frequency break down were characterized. During the Phase II project a final low power coupler will be built and tested before building two high power couplers. These high power couplers will be tested at cryogenic temperatures and characterized. Commercial Applications and other Benefits as described by the awardee: Reduced cost fundamental power couplers are an enabling technology for broad use of particle accelerators in many fields. These fields includes medical, defense, material processing and fundamental research.