Precise Alignment of Magnetic Field Centers of Quadrupole Magnets

on the Girder Taiwan Photon Source (TPS) project was proposed 3 years ago to build a 3GeV synchrotron light source. To achieve the designated ultra-low emittance of this new light source requires high precision positioning of storage ring magnets. Among all, the alignment of quadrupole magnets is of most importance since it directly affects the closed orbit of electron beams. Conventional on-site alignment of quadrupole magnets mainly relies on the theodolite performance. Most of theodolite measurement errors come from human-eye resolution and target precision. The cumulated errors could be in the order of 0.1 mm. In this report, a new alignment scheme is proposed to enhance the on-site alignment of quadrupole magnets for TPS project. To achieve the high precision requirements, a device possessing the advantages of both Vibrating Wire Method (VWM) and Position Sensing Detector (PSD) is suggested. The development of this alignment device is anticipated to provide a mechanism to better align the quadrupole magnetic centres on girder with positioning errors less than 30 μm. Taiwan Photon Source has been planned for several years in NSRRC and is in its final designing phase. Currently this 3GeV, ultra-low emittance synchrotron light source has a 486m storage ring with 24 periods and hundreds of magnets. The requiremen