1.3GHz RF Couplers with Double Windows Design and Self-Kept Vacuum

79412S05 Superconducting radio frequency (RF) cavities (of which the proposed International Linear Collider (ILC) will need several thousand) require ultra clean vacuum and surface cleanness. A break in a ceramic RF coupler window, with consequent inrushing of air and contaminants, would have catastrophic effects, and would require a long and expensive overhaul of the accelerator. To eliminate or minimize this potential risk, accelerators are increasingly being designed with double windows, with a vacuum space in between the two windows. However, the high costs of conventional double windows are prohibitive. This project will develop an innovative coupler design, along with efficient manufacturing approaches, that will simultaneously provide increased system reliability, cost reduction, and simplification. The novel double windows design will have self vacuum-keeping capability, will maximize the utilization of standard industrial parts, and will have a manufacturing approach that can meet the strong demands. In Phase I, an optimization study of the RF, mechanical, and thermodynamic performances will be conducted for a 1.3 GHz superconducting RF cavity coupler for application in the ILC. A one-step-brazing approach, using industrial standard components, will be developed and a novel double-window coupler design with a self-kept vacuum module will be completed. A testing module for feasibility studies will be fabricated to demonstrate the technology. Commercial Applications and Other Benefits as described by the awardee: Cost-effective, operation-reliable, and system-simplified RF coupler designs should be in demand worldwide for many DOE projects. Other technologies developed in the project should have wide applications in many industries where high voltage gradients in vacuums are required, such as the microwave tube industry, accelerator technology, and high vacuum industry.