Magnetic field measurements of the Nb3Sn common coil dipole RD3c

Goal of the LBNL Superconducting Magnet Program is to establish the technologies associated with very high field superconducting magnets, to provide cost-effective options for the next generation of high-energy colliders. Recent efforts have focused on the design, fabrication and test of Nb₃Sn common coil dipoles. The RD3b test has demonstrated operation at very high field and stress levels. RD3c is the first common coil prototype addressing field quality issues. A flat racetrack coil was wound on both sides of a central bore plate, using hard spacers to control the geometric field harmonics. The resulting coil module was inserted between the outer coil modules of RD3b, and pre-stressed using the reusable yoke and shell loading structure. In this paper, magnetic field measurements of RD3c are reported and compared with theoretical predictions.