A SQUID-Based Method to Measure Drift and Maintain Stability in Superconducting Magnets

SQUID sensors have the ability to measure changes in magnetic fields at and below the fT level. The ability to have detection coils in tesla level fields can allow measurements of drift in superconducting magnets at and below the part per billion (ppb)/hour level. We describe a method to measure drift and to use a negative feedback method to maintain central field stability at those levels. In addition, methods to measure superconducting joint resistance along with an NMR method to measure central field are described.