33.8 Tesla with a YBa2Cu3O7-x superconducting test coil

Abstract

A small coil was made and tested for the purpose of magnet technology development for YBa2Cu3O7-x (YBCO) high field coils. The coil has a winding inner diameter of 24 mm, outer diameter of 36 mm, and length of 46 mm in a pancake wound construction of 5 double pancakes. The YBCO conductor is SuperPower SCS4050 with 2×20μm of copper stabilizer. The coil was tested in the high field user facility of the NHMFL in a 31 T background field magnet. At this background field, the coil was operated to a current of 325 A and produced a field increment of 2.8 T for a record total field of 33.8 T. The average current density in the windings at full current was very high at 446A/mm2. The test was complicated by the accumulation of trapped helium gas about the coil due to the diamagnetic effect of helium at high field. Even though the coil operated at elevated temperature during the high field test, the coil performance was limited by mechanical degradation and not a critical current limit. © 2010 American Institute of Physics.