LAUSR

Next generation particle accelerators and fusion machines will greatly benefit from the development of low-inductance magnets capable of generating magnetic fields in excess of 16 T. Such magnets require high-temperature superconductors capable of carrying very high currents exceeding 5 kA at current densities of 400–600 Amm, such as Conductor on Round Core (CORC) cables and wires wound from RE-Ba2Ca3O7-δ (ReBCO, Re=rare earth) coated conductor tapes. CORC wires containing ReBCO tapes with 30 μm thick Hastelloy substrates have previously been demonstrated as a viable high-field magnet conductor that can be produced at long lengths. Further improvement of the performance and flexibility of CORC wires would benefit from the development of ReBCO tapes with even thinner substrates. SuperPower Inc. recently demonstrated ReBCO tapes based on 25 μm thick Hastelloy substrates that allow the development of thinner and more flexible CORC wires that meet the stringent performance requirements of high-field magnets. Several tapes containing 25 μm thick substrates were produced and analyzed, exhibiting critical current and cabling performance in-line with the current production level tapes with 30–50 μm thick substrates. Tape critical current was measured at 4.2 K and applied magnetic fields up to 31.2 T. Several CORC wires incorporating these tapes were manufactured by Advanced Conductor Technologies using similar winding procedures that previously resulted in high-quality magnet-grade CORC wires based on tapes with 30 μm thick substrates. The CORC wires were tested in an applied magnetic field up to 12 T after bending to a 63 mm diameter. A critical current as high as 6231 A (12 T, 4.2 K) was measured with an engineering current density (Je) of 678 Amm , which extrapolates to over 450 Amm at 20 T and is the highest current density reported in a CORC conductor to date. The combination of ReBCO tapes produced using 25 μm thick substrates and the ability to wind them into longlength, high-quality CORC magnet wires brings the development of low-inductance accelerator and fusion magnets that operate at magnetic fields exceeding 20 T closer to fruition.