Wake computations for undulator vacuum chambers of PETRA III

At DESY it is planned to convert the PETRA ring into a synchrotron radiation facility, called PETRA III. The wake fields of a tapered transition from the standard vacuum chamber to the small gap chamber of the insertion devices contribute significantly to the impedance budget of PETRA III. The computer codes MAFIA and PBCI have been used to determine the loss and kick parameters of the tapered transition. PBCI is a recently developed parallelized, fully 3D wake field code, which used a purely explicit, split-operator scheme to solve the Maxwell equation in the time domain.