Magnetostrictive Tuner for Radio Frequency Electron Beam Accelerator Cavities

141 Magnetostrictive Tuner for Radio Frequency Electron Beam Accelerator Cavities--Energen, Inc., 7 Riverside Avenue, Bedford, MA 01730-1528; (617) 271-9876 Dr. Chad H. Joshi, Principal Investigator Dr. Chad H. Joshi, Business Official DOE Grant No. DE-FG02-97ER82368 Amount: $75,000 Superconducting radio frequency cavities in particle accelerators are tuned by mechanically compressing the cavity, and the precision with which these cavities must be tuned requires micron-level positioning capability for the tuning mechanism. Furthermore, because of the high mechanical stiffness of the cavities, tuning mechanisms must provide high mechanical forces over a relatively small displacement. In addition, mechanical tuners have reliability problems operating in a cryogenic environment. This project will develop and demonstrate a reliable, precision tuning mechanism based on newly developed cryogenic magnetostrictive materials, which have saturation strains of 0.5 percent and can be used to build compact actuators. The resulting tuning mechanism will be more reliable, will reduce the heat leak into the cryogenic envelope, and will enable accelerator operators to actively fine tune the cavities to provide more reliable facility operation. In Phase I a prototype actuator will be designed and demonstrated. In Phase II the tuning assembly will be designed based on the prototype actuator, and the tuner will be tested under conditions that simulate the operational conditions expected for the radio frequency cavities. Commercial Applications and Other Benefits as described by the awardee: The results of this development effort will be a prototype of a reliable, cryogenic magnetostrictive precision positioner that has application to a variety of devices including valves, thermal links, radio frequency cavity tuners, and free electron lasers among other applications. Similar actuator designs can also be used for active vibration damping and motion sensors.