Magnetic field calculations of a permanent magnet insertion device for the advanced photon source

The magnetic fields of a hybrid undulator for the 7-GeV Advanced Photon Source (APS) were calculated. The 2-D geometries of the regular poles and the undulator´s end pole were chosen after finite-element analysis using the PANDIRA and PE2D codes. The field distributions in 3-D geometry were calculated using the TOSCA code. It is shown that the undulator dimensions should be chosen such that, that field integral along the z-axis for the operating gap of the undulator should be zero for the requirements of net zero positron beam deflection. It is noted that the TOSCA calculations in the 2-D limit agreed remarkably well with the results of PANDIRA and PE2D codes.