Development of cryogenic undulators and measurement equipment for PETRA IV

Abstract DESY is planning to upgrade its current storage ring PETRA III into the ultra-low emittance photon source IV. The H6BA cell design for IV lattice will allow insertion devices of up 4 m length in standard straight sections. In order some beamlines not only benefit from performance improvements by machine but also undulators, we started looking using advanced undulator schemes as well. We decided start cryogenically cooled permanent magnet undulators (CPMUs) based on (Nd,Pr)FeB magnets IV, since this technique has already been proven successfully various other facilities. present planned keepers, pole tuning mechanism well a testbed keepers under cryogenic conditions. show preliminary in-situ Hall-probe bench currently developed upcoming CPMUs.