Active Vibration Control of NLC Magnets

65050 To achieve a high degree of interaction between the positron and electron beams in the Next Linear Collider (NLC), the interacting beams must be aligned to within 1 nanometer. Low frequency vibrations from auxiliary equipment and from local ground vibration cause relative motion of the two beams and therefore must be dampened. Furthermore, longer-term ground motion requires periodic realignment of the beams through larger scale magnet movement. This project will develop a high force, active vibration damping system based on magnetic ¿smart¿ material actuators. The system consists of motion sensors, a high speed digital signal processor, and high force actuators based on magnetic smart materials. Phase I developed and demonstrated a reaction mass vibration control system, developed an innovative control algorithm, and characterized actuator motion sensors with the potential to achieve the nanometer stability required for the NLC. Active vibrational damping of the final focus magnets was achieved without requiring a physical connection from the magnets to ground because very little space is available for the installation of support structures. Phase II will develop and identify an advanced control algorithm, a cryogenic magnetostrictive actuator, a low noise power amplifier, along with high speed digital signal processors and motion sensors, to achieve stability at the 1nm level required for the NLC. 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 be applicable to semiconductor processing equipment, sensitive instrumentation, such as electron or tunneling microscopes, etc.