Superconducting filter coils for high homogeneity magnetic field

摘要

When a closed circuit is formed by joining superconducting wires with superconducting joints, the current in that circuit adjusts itself as required to maintain whatever total flux linkage the circuit had at the instant superconductivity was achieved. In particular, a closed circuit which first becomes superconducting under conditions of zero net flux linkage maintains zero net flux linkage as long as the circuit remains superconducting. By appropriately configuring a set of short-circuited superconducting coils, a field inside a volume described by the coils is kept substantially more uniform than it would be if the same volume were magnetized by the same source in the absence of the short-circuited coils. This property is used to insure that the volume within the coils exhibits improved magnetic field homogeneity.