In-Situ Electron Beam Processing for Radio Frequency Cavities

60957 Electrical breakdown is a critical factor limiting the voltage gradients that can be achieved in microwave cavities and accelerator structures, such as the 100 megawatt klystron being developed at the Stanford Linear Accelerator Center for the Next Linear Collider. Conventional approaches to increasing voltage breakdown thresholds are often expensive and time consuming. Using surface modification by in-situ irradiation with an electron beam, this project will develop an effective and practical method to increase voltage breakdown thresholds. As a result, both conditioning time and dark current levels in high gradient accelerating structures should be substantially decreased. In Phase I, the parameters of an electron beam appropriate for surface modification were determined. A prototype system design was developed to deliver the beam to the structure. Phase II will involve the construction and application of a system for surface modification of high voltage gradient structures. This includes consideration of the in-situ requirements. Commercial Applications and Other Benefits as described by the awardee: A new and effective means to increase voltage holdoff and lower dark current levels in radio-frequency structures should have application in medical, military, and research (particularly, the high-power klystrons that are under development at the Stanford Linear Accelerator Laboratory).