An Active Microphonics Control System

65041 Microphonic excitation in superconducting radio frequency (RF) structures causes a shift in the resonant frequency, making the structures less effective in transferring the RF energy into kinetic energy of the particles. As a result, a larger RF power source and a larger helium refrigerator are needed, increasing capital costs and reducing overall reliability. This project will develop an active microphonics damping system based on magnetic ¿smart¿ material actuators and high speed digital signal processing. These actuators will be designed to operate efficiently at cryogenic temperatures. In Phase I, the requirements of a microphonics control system were obtained through discussions with engineers at the Thomas Jefferson National Accelerator Facility, the National Superconducting Laboratory, Argonne National Laboratory, and the Spallation Neutron Source, and a prototype actuator was built and tested. The tests demonstrated the feasibility of using magnetostrictive materials for cavity tuning: satisfactory load handling capacity, magnetostriction, and response time were shown. Phase II, will develop a working tuner, install it on a superconducting RF cavity, measure its performance characteristics and sensitivity, and develop a comprehensive design for a control system. Commercial Applications and Other Benefits as described by the awardee: Active vibration control is a serious problem in a wide range of applications. The low frequency and high amplitude damping capability should have applicability to semiconductor processing equipment and other sensitive instrumentation such as electron or tunneling microscopes.