Joining of Ceramic Structures for Advanced High Energy Accelerators

73184S03-I Increasing the voltage gradient of radio frequency (RF) linear accelerator structures is an ongoing objective within the High Energy Physics Program of the Department of Energy. Recent advances in the use of dielectric loaded waveguides hold the promise of fulfilling this need. However, configuring the dielectric within the metal waveguide requires precise manufacturing and assembly technologies to negate field enhancement at the joints and to assure dielectric constant uniformity along the waveguide structure. This project will develop technology for joining ceramic tubes while maintaining the crystalline microstructure and dielectric properties. It is based on a recently developed technique for high-frequency, high-powered, focused-beam microwave heating that heats in only a small region around the joint area. In Phase I, hot-pressed alumina tubes will be joined using a proprietary reactive braze in a microwave beam heating system. The tubes will be evaluated for microstructural uniformity and crystallinity in the joined area. Lastly, the tubes will be assembled and evaluated in a cold-test facility for power transmission and impedance matching. Commercial Applications and Other Benefits as described by awardee: This technology should be applicable to the one-meter-long tubes that will be needed for the dielectric loaded waveguide accelerator structures being developed for the NLC. In addition, the ability to join advanced ceramics in specific well-defined areas without significant heating of the surrounding material should find widespread use.