Characterization of the Support and Drive System of the PETRA III APPLE Undulator

Helmholtzzentrum Berlin has built an APPLE II undulator for the storage ring PETRA III. The device has a total length of 5m and a minimum gap of 11mm. The high magnetic forces in particular in the inclined mode have been analyzed by means of finite element methods (FEM). Specific mechanic components such as flexible joints have been optimized to cope with the gap‐ and shift‐dependent 3D‐forces and a sophisticated control and drive system has been implemented. After completion of the device, detailed laser interferometer measurements for all operation modes have been performed. The data are compared to the FEM simulations.