Phase error reduction in superconductive undulators using induction shimming

As shown in a first proof of principle experiment, induction shimming can constitute a simple and efficient method of increasing the field quality of superconductive undulators. Although previous measurements on a single undulator half were successful in giving a qualitative understanding on hysteresis in the shim coils, it was found that the measurement setup needs improvement for meaningful calculations of the phase error reduction. Presented here are the first results on phase error reduction with induction shimming, using a measurement setup with improved accuracy. Theoretical results on the coupling between shim coils, important for the function of the shim system and for an extension to full length undulators, are also presented in this contribution.