Bahrdt, J.; Ivanyushenkov, Y.: EFFECTS OF GEOMETRICAL ERRORS ON THE FIELD QUALITY IN A PLANAR SUPERCONDUCTING UNDULATOR. In: Proceedings of IPAC 2012, New Orleans, Louisiana, USA. , 2012, p. 708-710

Short-period superconducting undulators are being developed at the Advanced Photon Source (APS). A 21- period undulator prototype is being fabricated. Later, the short coil will be replaced with a longer one using the same cryostat. A high quality magnetic field with a phase error of 2 degrees rms was achieved in the prototype magnets due to accurate winding of the superconducting coils on the precisely machined formers. Manufacturing meterslong undulator magnetic structures is a challenging task. A detailed understanding of the impact of geometric tolerances on the spectral performance is essential and appropriate manufacturing techniques have to be applied. The magnetic fingerprints of positioning errors of the superconducting windings in a planar structure are derived. Using these data the field profile of a long nonideal undulator magnet is then built and analyzed with respect to phase errors. The spectral performance degradation due to random and systematic geometric errors is presented.