THE APPLICATION OF VISCOELASTIC DAMPING MATERIALS TO CONTROL THE VIBRATIONOF MAGNETS IN A SYNCHROTRON RADIATION FACILITY

摘要

The Advanced Photon Source at Argonne National Laboratory is a facility designed to produce extremely brilliant X-rays for materials, chemistry, and medical research. In this facility, positrons are first produced and accelerated to energy levels of 7-GeV. The positrons are then injected into a 1104-meter circumference storage ring where they circulate, for periods up to 18 hours, and emit high-intensity X-rays as the circulating beam is oscillated by insertion devices. The beam is positioned and its size controlled by large electromagnets. The magnets are mounted on 200 individual girder assemblies, with each assembly having several magnets mounted on it. Of prime concern are the girder assemblies supporting the quadrupoles, or focusing, magnets. These magnets must satisfy very stringent vibration criteria, with motion restricted to less than a micron over a broad frequency range. Therefore, amplification at resonant frequencies of the girder assemblies must be minimized. To accomplish this, various viscoelastic-damping materials and their placement in the system were evaluated. As a result of the study, dynamic-magnification factors were reduced to a value of 5 with no detectable increase in static deflection. The damping materials and methods used to accomplish this in massive systems of 7,500 kg or greater, where displacements are on the order of 0.1 micron or less, will be useful in many less-demanding situations.