Field Measurements on Curved Superconducting Magnets

The Facility for Antiproton and Ion Research (FAIR) and the Nucleon-based Ion Collider fAcility (NICA) will use fast ramped superconducting magnets with a curvature of 55 m and 15 m respectively. Compared to normal conducting machines with equivalent field strength, the field quality of superconducting magnets is very sensitive to the real geometric details due to its much smaller yoke size. Further the closed cryostat makes it tedious to add correction elements at a later stage. Therefore the measurements must provide a reliable full information of the magnetic field strength, the field direction as well as the field homogeneity and its harmonics. We outline the theory developed, show principal useable coordinate systems, present their features, and outline how the measurement can be made in practice next to first test results obtained on measuring the curved full size model dipole for the heavy ion synchrotron SIS100.