Large predicted self-field critical current enhancements in superconducting strips using magnetic screens

A transport current distribution over a wide superconducting sheet is shown to strongly change in the presence of bulk magnetic screens of a soft magn et with a high permeability. Depending on the geometry the effect may drast ically suppress or protect the Meissner state of the sheet through the enha ncement or suppression of the edge barrier critical current. The total tran sport current in the magnetically screened Meissner state is expected to co mpete with the critical current of the flux-filled sheet only for samples w hose critical current is initially essentially controlled by the edge barri er effect.