Theory of Josephson media in a high-temperature superconductor - Eddies and critical magnetic fields

It is shown that, if a high-temperature superconductor is divided into granules whose boundaries are Josephson junctions, then the Meissner state breaks down in a very weak magnetic field Hc1, weaker than the earth's magnetic field. It is noted that experimentally determined lower critical fields which significantly exceed this value should be compared with another critical field Hi, in the case of which eddies begin to penetrate into the granule volume.