Test of an Electromagnetic Shimming Concept for Superconducting Undulators

Accurate magnetic field measurements are a prerequisite for the characterization and optimization of undulators. At the synchrotron light source ANKA there is an ongoing R&D program for superconducting insertion devices. Within this program a test stand for precise magnetic field measurements of superconductive coils was designed, built and installed at the Research Center Karlsruhe. Comprehensive magnetic measurements are performed to confirm the magnet design and to detect or correct field imperfections resulting from the manufacturing process. The magnetic field is measured along a fixed direction by Hall probes with a positioning precision of 3 mum. A NbTi undulator prototype with local correction coils was built to verify the performance of the superconductor and the shimming concept. In this contribution we describe the measuring test station and preliminary tests results including the efficiency of the shimming concept.