Development of the manufacturing and QA processes for the magnetic modules of the LCLS-II soft X-ray undulators
Abstract
A new free electron laser being built at SLAC National Accelerator Laboratory, the Linear Coherent Light Source II (LCLS-II), will use 21 soft x-ray undulators (SXR) and 32 hard x-ray undulators (HGVPU). Lawrence Berkeley National Laboratory (LBNL) is responsible for the design and manufacturing of all variable-gap, hybrid permanent-magnet undulators. The physics requirements for the undulators specify a longitudinal pole misalignment maximum rms error of 25 µm and a vertical pole misalignment maximum error of 50 µm. In addition, magnet positioning critically influences the gap-dependent field properties due to saturation effects at the smallest operational gaps. This paper discusses the manufacturing and QA methods developed to carefully control the longitudinal and vertical pole and magnet positions during undulator production. Inspection results are discussed based on data gathered during construction of a prototype as well as pre-production soft x-ray undulator.