The 90-mm period undulator for SRRC

The U9/SRRC undulator has recently been completed by STI Optronics Inc. (STI) for use at the Synchrotron Radiation Research Center (SRRC) in Hsinchu, Taiwan, R.O.C. This 4.5-m long, 90-mm period wedged-pole hybrid undulator builds on several aspects of previous STI designs while including a number of significant enhancements. The magnetics are based on the wedged-pole geometry with additional side magnets. At the 19-mm minimum gap the peak field is in excess of 1.28 T with less than 3 degrees of optical phase error. The magnetic structures are mounted on stainless-steel strongbacks and are connected to the gap separation structure in a method to specifically reduce optical phase errors. The magnetic structure is positioned by four closed-loop servomotors within cast aluminum C-frames. The entire structure is mounted onto a retraction system to easily move away from the vacuum chamber for servicing. The device is controlled by a real-time VME-based control system capable of autonomous local and remote operation.