Electromagnetic Design, Fabrication, and Test of LPF1: A 10.2-T Common-Coil Dipole Magnet With Graded Coil Configuration

R&D of high-field accelerator magnets is ongoing at the Institute of High Energy Physics for the prestudy of high-energy accelerators in the future. As the first step, a 12-T subscale common-coil dipole magnet named Let the Proton Fly (LPF1) with two 7-mm apertures and graded coil configuration was designed, fabricated, and tested. With 4 NbTi double-pancake racetrack coils outside and 2 Nb
₃
Sn double-pancake racetrack coils inside, this hybrid dipole magnet was designed to provide a 12-T main field in two apertures operating at 6100 A. The load line ratio is 83% @ 4.2 K for the designed current and field. To reduce the field enhancement at the ends of the coils, the coils were designed with different lengths. All of the six coils were wound with superconducting Rutherford cables and impregnated with epoxy CTD-101k. Bladders and keys technology was used to prestress coils during the assembly of LPF1. A 0.1 Ω dump resistor and a voltage-dependent varistor were used for the quench protection during the test of LPF1. LPF1 was tested at 4.2 K under the self-field and a field plateau was shown around 10.2 T after the 13th quench. The parameters of the design, process of the fabrication, and the test performance of LPF1 are presented in this paper.