MAGNETIC-FLUX PENETRATION AND CRITICAL-CURRENT IN LONG PERIODICALLY MODULATED JOSEPHSON-JUNCTION

The critical state of the magnetic field in a periodically modulated l arge Josephson junction is studied. A critical value g(c) of the dimen sionless modulation strength g is shown to exist. Critical profiles of the magnetic field and depinning threshold currents are obtained both in g < g(c) and g > g(c) regions using a unified approach. It is foun d for g < g(c) that a magnetic-field threshold value H(t) (g < g(c)) e xists, above which the magnetic field penetrates into the whole juncti on. The total critical current is finite in this case even for infinit e junction. If g > g(c) the large-scale critical profile is linear and the threshold current density is finite. We have obtained its depende nce on g down to the lowest possible value g = g(c).