Progress in Design of Permanent Magnet Dipole-Quadrupoles with Longitudinal Gradient for the PETRA IV Storage Ring

Abstract PETRA IV is an upgrade project planned to replace the Synchrotron light source PETRA III. The main objective is to reduce the horizontal emittance to 20 pmrad. This nominal emittance will be achieved by a hybrid six bend achromat lattice(H6BA). To fulfill the requirement of this lattice, three different types of permanent dipole magnets will be used which include a combined-function dipole-quadrupole magnet with both longitudinal and transverse gradient (DLQ). The use of permanent magnet material for the combined-function dipole-quadrupole magnets is particularly useful for achieving a compact design, but also for reducing power consumption during operation. This paper presents the overall progress in this DLQ development, the expected magnetic field characteristics obtained from 3D Radia simulations, and advanced design details like the cross-talk with neighboring quadrupole magnets. The status of the present prototype activities is also discussed.