Peculiarities of voltage-current characteristics of asymmetrical superconductive tunnel junctions observed in the measurements under «voltage source» regime

The peculiarities of static downward voltage-current characteristics of Sn-I-Pb tunnel junctions have been investigated in the voltages range (Δ_Pb - Δ_Sn)/e < v < (Δ_Pb + Δ_Sn)/e (where Δ_Pb and Δ_Sn are the energy gaps of Pb and Sn, respectively) at transition shift under «voltage source» regime. The character of these peculiarities which varies with the load resistance, temperature and external magnetic field as well as comparison with the known experimental results obtained for the Josephson voltage - current characteristics branches and the existing theory suggests that the descending branch is defined by the processes associated with the relaxation oscillations present in a system.