Magnetic measurements and tuning of the DUV-FEL undulator

(TU-3-16)

S. Gottschalk, L. Campbell  

STI Optronics Inc

The DUV-FEL being built at Brookhaven National Laboratory is a seeded SASE FEL that will operate at 0.2129 microns. It uses the continuous, 10 meter long NISUS undulator originally built for the Boeing High Average Power FEL in 1987. The undulator is a 3.89 cm period wedged pole hybrid with SmCo5 magnets. It was installed at BNL and tuned by STI Optronics for the rigorous requirements of the DUV-FEL. Measurements consisted of overlapping 3.0-meter segments. Passive field tuning without external corrector coils was used. The predicted performance over the entire 10 meter length of the undulator is 4 degrees phase error, 74 micron peak-to-peak trajectory deviation and 15 micron rms deviation at 197 MeV. Initial and final magnetic measurements will be presented as well as the tuning techniques and mapping protocols followed to insure precise and accurate scans were being made from overlapping data sets.