Critical currents of type ii superconductors in non-transversal magnetic fields

The force on flux lines near narrow defects elongated in the direction of the transport current is calculated. This force, together with the maximum interaction forcek_m on the central flux line element, gives the volume pinning forceF_p on the flux line lattice. The dependence ofk_m (and of the critical current densityj_c) on the angle between the magnetic field and the transport current is calculated for different defect dimensions (with respect to the coherence length of the superconductor) and compared with the experimental results. We obtainj_csin^–n , where 1n3 in dependence on the defect dimensions and on the angle interval. The possibility of testing theF_p k_m² dependence of the statistical theory of pinning is proposed.