Latest Experience on Insertion Devices at the National Synchrotron Light Source-II

Abstract

 National Synchrotron Light Source-II (NSLS-II) is the latest storage ring of 3 GeV energy with the horizontal emittance of the electron beam being 0.9 nm.rad. Nine In-Vacuum Undulators (IVUs) are utilized at the NSLS-II as of February 2016. All IVUs have a unique side window derived from the experience from the CHESS facility in Cornell University. An R&D activity called “Vacuum Seal Test” was conducted to ensure the viability of aluminum wire seal. Another R&D activity to develop a measurement system for Cryogenic Permanent Magnet Undulator (CPMU)¹⁾ was also performed. Other in-air devices, namely damping wigglers (DWs) and elliptically polarizing undulators (EPUs) utilize extruded aluminum chambers with Non-Evaporable Getter (NEG) coating. The beam-based integral estimates were obtained from the virtual kicks at the upstream and downstream of the undulator that best fit the measured orbit distortion in a model lattice with Tracy. In some cases, there are fairly large discrepancies between magnetic measurement data and observed integrals by the beam. Beam studies were carried out to explain the discrepancies mentioned earlier. The latest experiences on ID development and commissioning are discussed in conjunction with related activities in the world.