Superconducting Magnet Performance for the LCLS-II Project

The new LCLS-II Superconducting Linear Accelerator Cryomodules are under construction at Fermilab. Installed inside each Super Conducting Radio Frequency (SCRF) Cryomodule is a superconducting magnet package to focus and steer an electron beam. The iron-dominated magnet package has conductively cooled racetrack-type coils with both quadrupole and dipole windings. For ease of installation, the magnet is splittable in the vertical plane. To confirm magnet specifications, we performed a quality acceptance in a liquid helium bath for quench testing, and we performed high-precision magnetic field measurements. The magnetic and mechanical center alignment was investigated using the vibrating wire technique. Several prototypes and all production units have been tested. This paper summarizes the magnetic measurements and quench test results of all tested units, including comparison of performance and repeatability between different units.