In-vacuum, Cryogen-free Field Measurement System for Superconducting Undulator Coils

The performance of superconducting insertion devices (IDs) depends strongly on the magnetic field quality. Before installing IDs in synchrotron light sources the characterization and precise measurements of their magnetic properties are of fundamental importance. Improvements in magnetic field measurement technology of conventional, i.e. permanent magnet based IDs, made significant progress during the last years and push the capabilities of synchrotron light sources. For superconducting IDs similar major developments are necessary. As a part of our R&D program for superconducting insertion devices we perform quality assessment of their magnetic field properties. This contribution describes details and challenges of the cryostat and measurement setup assembly to perform magnetic measurements of the local field and of the field integrals of superconducting undulator coils in a cold invacuum (cryogen free) environment. The focus will be on the outcome of the final acceptance test together with results of first tests performed with a conduction cooled mock-up coil.