Performance of the SRRC-U10P quasi-periodic undulator

SRRC has constructed a 2-meter long quasi-periodic undulator from a conventional undulator to produce an irrational harmonics radiation spectrum. A higher peak magnetic field was employed in a quasi-periodic position by adjusting the side magnet blocks and the shims to optimize the photon energy shift range and flux suppression ratio on the third and fifth harmonics of the spectrum. The magnetic design and the results of magnetic field measurement are reported. In addition, the spectral characteristics and flux are presented according to the computed and measured magnetic fields. The photon spectra of a conventional and a quasi-periodic undulator are compared.