Abrikosov monopole vortices and their images in a circular Josephson tunnel junction

We present the results of a numerical simulation of the dependence of the Josephson critical current on the parallel magnetic field in the presence of a large number of Abrikosov 'monopole' vortices for the case of a circular junction. The influence of the junction edge on the distribution of the magnetic field of each vortex was taken into account by introducing image monopole vortices. Our simulations show that the dependence of the Josephson critical current on the parallel magnetic field (the I-c vs H-par dependence) critically depends on the existence of a vortex located near the center of the junction. The simulation data are compared with experiments made on circular Nb/Al - AlOx/Nb junctions. A good agreement has been found between calculated and I-c vs H-par dependences measured after the application of a perpendicular magnetic field.