Vortex Convection Nonlinearity of Ac Response of Superconductors with Weak Links

The electrodynamics of a high-T(c) superconductor with a network of numerous weak links (the Josephson medium) in the low-field mixed state have been analysed. The AC response to an electromagnetic wave is governed by the motion of vortices of very large size (hypervortices). The nonlinear effect of the vortex convection has been taken into account, and the second harmonic amplitude calculated.