Critical current of oriented high-T-c superconductors

The magnetic-field dependence of the critical current density in simply connected Josephson medium (as an element of multiply connected superconducting ceramics) has been considered semiphenomenologically. The results are used to analyse the properties of the transport of current in granular superconductors of finite dimensions. It has been shown that the field dependence of the critical current density J(c)(H) alpha(1 - H/H-0). This is in correspondence with the available experimental results. The dependence of the critical current density on contact dimensions of the weakly coupled grains is discussed.