Refurbishment of a used in‐vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source‐II ring

The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS‐II. There were four in‐vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini‐gap undulator (MGU‐X25, to be renamed IVU18 for NSLS‐II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS‐II. At the time of construction, IVU18 was a state‐of‐the‐art undulator designed to be operated as a cryogenic permanent‐magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS‐II ring, the transition region was redesigned. The control system was also updated to NSLS‐II specifications. This paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning.