A High Force Actuator for SRF Cavity Tuning--Energen, Inc., 17 D Sterling Road, Billerica, MA 01862-2518; 978-671-5400
Dr. Chad H. Joshi, Principal Investigator
Dr. Chad H. Joshi, Business Official
DOE Grant No. DE-FG02-99ER82784
Amount: $750,000

Superconducting radio frequency (SRF) cavities, used in high- and medium-energy physics research, are tuned by mechanically squeezing them along their axis. The tuner actuator must produce a force of several thousand pounds and have submicron positioning resolution. This pro-ject will develop an SRF tuning mechanism based on newly developed cryogenic magnetostrictive materials; these materials have saturation strains of 0.5% and can be used to build compact actuators. In Phase I, a high force linear stepper motor employing magnetostrictive materials was designed and built. It had a motion range of 10 millimeters, an output force capability of 2200 N (500 lbs), and submicron positioning resolution. The force capability was limited by the static frictional brake of the clamps of the stepper motor. A mechanical leverage system was designed to amplify the force capability to provide the 22 kN (5000 lbs) force necessary to tune the SRF cavities for the Department of Energy Jefferson Laboratory upgrade. Phase II will develop more cost-effective techniques for manufacturing the magnetostrictive materials, and their mechanical, magnetic, electrical and thermal properties will be characterized. The goal is to design and build stepper motor tuners capable of providing a wide tuning range.

Commercial Applications and Other Benefits as described by the awardee: These magne-tostrictive tuners should provide improved performance of superconducting RF cavities used