Performance of a NSRRC In-Vacuum Undulator

An advanced undulator technology is critical for highly brilliant synchrotron radiation in a third-generation light source. Taiwan Photon Source (TPS) is a light source of intermediate energy, and a short magnet period of an undulator is desired for experimental stations using hard X-rays. In-vacuum undulators have been delivered and tested at the NSRRC site before installation in the storage ring. The vacuum tests were performed first to ensure an ultra-high vacuum (below 2 ×10^-10 torr). Magnetic measurement is comprised of laser alignment system that was developed at NSRRC. The results show satisfactory field repeatability after assembly of the vacuum chamber, because phase errors of both undulators are less than 3^°. Baking an undulator was performed to achieve an ultra-high vacuum. Here, we describe the results from the acceptance tests.