Robust Radio Frequency Accelerator Structures at 34.272 GHZ

65074 Continued progress in high-energy physics demands a new high energy electron-positron collider, which in turn requires new high-power, high-frequency radio frequency (RF) technology. Development of RF technology at 34.272 GHz could allow three times the accelerating gradient compared to 11.424 GHz. This project will develop a novel test device for subjecting RF structures at 34.272 GHz to high thermo-mechanical stress with pulsed temperature rises as high as 500¿C. The device would allow structure lifetime tests to be conducted in a relatively short time, thereby evaluating the suitability of various materials and fabrication processes for future long-life high-gradient accelerators. In Phase I, detailed analytical and numerical studies to optimize design of the 34.272 GHz demountable rf cavity for pulse surface heating tests were carried out, and a cold-test version of the cavity was built and tested. Design features were incorporated that suppress RF breakdown, to allow for a clear evaluation of the effects on cavity surface degradation from thermo-mechanical surface stress. Phase II will design and construct the high-power test-cavity setup, develop and refine diagnostics, and perform experimental investigations of metal fatigue caused by pulse heating for copper, the most common material in accelerating structures. Commercial Applications and Other Benefits as described by the awardee: A robust accelerating structure, developed as a result of this program, would represent a business opportunity with a potential in the range of $500 million. Test results at 34.272 GHz could also be used to determine the lifetimes of accelerator structures at other frequencies.