Stabilization of dry-wound high-field NbTi solenoids

Dry-wound, Formvar-insulated NbTi superconducting solenoids are frequently used for small-bore and low-field applications because of their low manufacturing costs. The more widespread use of dry-wound coils for large-bore and high-field applications has been limited by their tendencies toward conductor-motion-induced degradation. Simple models for estimating the occurrence of conductor-motion disturbances in dry-wound solenoids are described. These models were used to design and analyze the training behaviors of three small, high-field NbTi test coils. The experimental results suggest that stabilization is best achieved by forcing all potential conductor motions to occur during low-field portions of the magnet's energization sequence, where its stability margin is greatest.>