Analog-Computer Studies of Josephson Radiation Effects

Equations characterizing a Josephson junction coupled to a resonant cavity driven by an rf voltage have been programmed for an electronic analog computer. Modifications in the dc $V-I$ characteristic of the junction, for both constant-voltage and constant-current load lines, as well as the power spectrum in the cavity, were observed as a function of the parameters: resonance frequency and $Q$ of the cavity, frequency and amplitude of the applied rf voltage, and strength of coupling between junction and cavity. Many of the nonlinear, parametric effects observed can also be understood analytically on the basis of the approximation that the cavity electric field contains only a single frequency component.