Noncontacting alternating current surface probe measurements of transport critical currents in a slab geometry

Determination of the critical state full penetration field of a slab of YBa2Cu3O7−x by induced screening currents is described. This geometry allows spatial measurements to be made by scanning with the probe coil even though nonuniform demagnetization effects are present. The onset of transport current dissipation was observed by the reduction of diamagnetism and appearance of dissipation in the probe coil induced current. The results are compared to contact four-point probe direct current measurements and to the critical state model.