Design, fabrication, and characterization of a high-field high-temperature superconducting Bi-2212 accelerator dipole magnet
Tengming Shen, Laura Garcia Fajardo, C. Myers, A.R. Hafalia, José Luis Rudeiros Fernández, D. Arbelaez, Lucas Brouwer, S. Caspi, P. Ferracin, S.A. Gourlay, M. Marchevsky, Ian Pong, S. Prestemon, Reed Teyber, Marcos Turqueti, Xiaorong Wang, Jianyi Jiang, Ernesto Bosque, Jun Lü, Daniel Davis, U.P. Trociewitz, E. E. Hellstrom, D. C. Larbalestier
Abstract
The use of high-field superconducting magnets has furthered the development of medical diagnosis, fusion research, accelerators, and particle physics. High-temperature superconductors enable magnets more powerful than those possible with Nb-Ti (superconducting transition temperature ${T}_{c}$ of 9.2 K) and ${\mathrm{Nb}}_{3}\mathrm{Sn}$ (${T}_{c}$ of 18.4 K) conductors due to their very high critical field ${B}_{c2}$ of greater than 100 T near 4.2 K. However, the development of high-field accelerator magnets using high-temperature superconductors is still at its early stage. We report the construction of the world's first high-temperature superconducting ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{x}$ (Bi-2212 with ${T}_{c}$ of $\ensuremath{\sim}82\text{ }\text{ }\mathrm{K}$) accelerator dipole magnet. The magnet is based on a canted-cosine-theta design with Bi-2212 Rutherford cables. A high critical current was achieved by an overpressure processing heat treatment. The magnet was constructed from a nine-strand Rutherford cable made from industrial 0.8 mm wires. At 4.2 K, it reached a quench current of 3600 A and a dipole field of 1.64 T in a bore of 31 mm. The magnet did not exhibit the undesirable quench training common in Nb-Ti and ${\mathrm{Nb}}_{3}\mathrm{Sn}$ accelerator magnets. It quenched a dozen times without degradation. The magnet exhibited low magnetic field hysteresis ($<0.1%$) as measured by a cryogenic Hall sensor. It was fast cycled to 1.47 T at $0.54\text{ }\text{ }\mathrm{T}/\mathrm{s}$ without quenches. This work validates the canted-cosine-theta Bi-2212 dipole magnet design, illustrates the fabrication scheme, and establishes an initial performance benchmark.