A Tuning System for Spoke Cavities

72511S03-I The Rare Isotope Accelerator (RIA) facility is considering the use of spoke cavities as replacements to elliptical cavities. The tuning systems for spoke cavities, consisting of a cold motor and a screw drive with a piezo actuator in series, have reliability problems operating in a cryogenic and vacuum environment. Due to the high mechanical stiffness of the cavities, these tuning mechanisms must provide high mechanical forces over a relatively small displacement. This project will develop and demonstrate a reliable, comprehensive tuning system based on cryogenic magnetostrictive materials. Cryogenic magnetostrictive materials have saturation strains of 0.5% and can be used to build compact actuators. In addition to more precise tuning, a tuning mechanism based on magnetostrictors will be more compact and enable accelerator operators to actively fine-tune the cavities to provide more reliable facility operation. Phase I will develop a detailed design for a tuner that can provide a broad tuning range and fast response tuning for a spoke cavity. Engineering tests will be performed to prove key elements of the conceptual design. Commercial Applications and Other Benefits as described by awardee: A reliable cryogenic magnetostrictive comprehensive tuning system for spoke cavities should help reduce the radio frequency (RF) power requirements of spoke cavities, in effect reducing the cost of the facility. The tuning system should have application in a variety of devices including valves, thermal links, RF cavity tuners, free electron lasers, active vibration damping, and motion sensors.