Superconducting DC/AC magnetic system for loss and magnetization experiments operating up to 50/60 Hz

Loss and magnetization measurements provide very complex information on the electromagnetic properties of superconductors. Measuring methods frequently require DC magnetic field with AC superposition at various frequencies. The simplest system to produce this field seems to be a coaxial magnet system consisting of an outer DC coil with an inner AC insert. However, this configuration results in strong coupling between the AC and DC coils. As a result, the DC coil performance is strongly degraded. The authors present a solution of this problem, based on the use of two coaxial AC coils instead of one. The geometrical configuration which they developed reduces the coupling of AC coils with the DC coil almost perfectly. Using the described concept, the authors projected, realized and tested a DC/AC superconducting magnet system which can produce a DC magnetic field of up to 4 T with AC superposition varying from 0.4 T (B/sub DC/=4 T) up to 1.1 T (B/sub DC/=0 T) and frequency up to 50/60 Hz.<>