Origination and oscillations of normal zone in superconductors

Dynamics of normal (N) zone regions (resistive domains) in uniform and nonuniform superconductors has been investigated both theoretically and experimentally. An analytical theory has been proposed to describe the resistive domains (RD) dynamics in nonuniform superconductors with the alternating current. The origination and localization of RD have been considered. The self-exited relaxation oscillations of the voltage were observed experimentally. The oscillations are due to the self-exited ones of the RD length when the inductance of the circuit is large enough. The superconducting sample in our experiment was made from the multifilament Nb-40%Ti cable, the characteristic values of the oscillations frequency f and the inductance L were of the order of 1 Hz and 20 μH respectively. The theory proposed is in a good agreement with the experiment.