The distribution of the transport current in a cylindrical sample of type-2 superconductor in a longitudinal magnetic field

The distribution of the magnetic field produced by the current inside the slot in Pb+23 at %In samples placed in a longitudinal magnetic field was measured by means of a moving Hall probe. It has been shown that the transport current flows only in the surface region up to the magnetic fields close to Hsub(c2), which made the critical current density concept rather questionable. Current penetration over the whole cross-section was connected with the appearance of a longitudinal voltage along the sample. The sample with higher pinning had the lower value of critical current. The comparison of measured field distributions with the latest theoretical model was made. (author)