Vortex penetration in shunted type II superconducting strips

Abstract

To investigate the magnetic properties of electrical contact between the superconducting filaments in a multifilament tape, this paper studies the vortex motion across a simpler planar model of the tape, namely an array of superconducting film strips with shorted ends, a 'shunted-x-array'. The vortex motion visualized by magneto-optical imaging is discussed when external currents, magnetic fields, and both simultaneously are applied. When transport current alone is applied, the flux distribution in the shunted-x-array strips is very similar to that in a single strip. However, the behaviour is completely different in the presence of an external magnetic field. The induced current flows around the entire sample to shield the inner region, while the vortices penetrate first into the outermost strips, and then into the next strips in turn as the field increases. For this case, the flux distribution is symmetrical about the central vertical line of the sample. When current and field are simultaneously applied, the vortex penetration into the sample is no longer symmetrical because the resultant current is not a simple linear superposition of the induced and applied currents.