Design of Strain-Limited Bi-2223 Insert Coils for High-Field Magnets

摘要

High field solenoid coils made with HTS conductors are limited primarily by total strain and then by critical current. A detailed accounting of all the sources of mechanical strain on a coil is an essential part of the design. Those sources include winding tension, bending about the coil axis, bending to form the layer transition, compression from overbanding, differential thermal contraction, magnetic hoop strain in the radial and axial directions, and thermal expansion from quenches. A design example for a high-field insert coil made with Sumitomo Type HT-NX Bi-2223 conductor is presented, with each of the relevant strains computed explicitly.