Performance comparison of Nb3Sn magnets at LBNL

The Superconducting Magnet group at Lawrence Berkeley National Laboratory has been successfully developing Nb₃Sn high-field dipole magnet technology for the last ten years. Noteworthy magnet tests include D20 (50 mm bore, 4-layer cos θ, 12.8 T, accelerator quality dipole), and recent racetrack dipoles: 1) RT1 (2-layer, 12 T, no bore, no training), 2) RD3b (3-layer, 14.7 T, 10 mm bore), 3) RD3c (3-layer, 10 T, low-harmonics 35 mm bore), and 4) some small Nb₃Sn magnets that utilized new technology. The performance of these magnets is summarized, comparing 1) cable and magnet geometry parameters, 2) training behavior, 3) ramp rate sensitivity, 4) RRR measurements, 5) peak temperatures and voltages, and 6) fast flux adjustments that occur during ramping.