Effect of Insertion Devices Tapering Mode of Operation on the MAX IV Storage Rings

Abstract: Tapering is a mode of operation of insertion devices that allows the users to perform scanning in a range of photon energies. NanoMAX, BioMAX and BALDER are all beamlines of the 3 GeV MAX IV storage ring and will provide this special mode of operation for their users. In this thesis, the spectra of NanoMAX and BioMAX while operating with tapering were studied and feed forward tables that cancel out the closed orbit distortion caused by the insertion devices were generated. Moreover, a study of the nature of the closed orbit distortion was performed, aiming at simplifying the feed forward table measurements that can currently be quite time consuming. In addition, the effect of BALDER, which is a wiggler and currently the strongest insertion device in the storage ring, on the electron beam was studied. Apart from the feed forward table that corrects for the closed orbit distortion, BALDER induces a beta beat and tune shift which has to be eliminated in order to make the insertion device transparent to the electron beam. This correction is needed in order to keep the beam life time unaffected and ensure a stable operation. For this reason, a two-stage correction scheme was proposed. First, a local correction with the quadrupoles adjacent to BALDER was performed in order to eliminate the beta beat induced by the wiggler. As a second step a global correction was applied. The aim of the global correction is to bring the tune back to the design values.