Critical dynamics and plastic flow in disordered Josephson junction arrays

We present numerical simulations of Josephson junction arrays with positional disorder. We study their IV characteristics and vortex dynamics as a function of disorder. We find that above the critical current ${\mathit{i}}_{\mathit{c}}$ there is a plastic flow of vortices and antivortices through channels, characterized by strong fluctuations of the total vorticity. For large currents there is a crossover to homogeneous flow without vortex fluctuations. We also study the dynamical critical behavior close to ${\mathit{i}}_{\mathit{c}}$ in the gauge glass model, calculating critical exponents for the voltage onset and voltage fluctuations.