FLUCTUATIONS OF THE CRITICAL-CURRENT THROUGH JOSEPHSON-JUNCTIONS WITHDIRTY NORMAL-METAL BARRIERS

Josephson currents in superconductor-normal metal-superconductor junct ions are studied numerically when the normal metal region is in the di ffusive regime. The average critical current and the fluctuations of t he critical current are calculated as a function of the length of the normal metal region L. In the case where L is shorter than the coheren ce length of the superconductor xi, the magnitude of the fluctuations is shown to be of order eDELTA/hBAR (DELTA is the pair potential). Whe n L is several times as long as xi, numerical results suggest that the fluctuations become of order e square-root DELTAE(c)/hBAR (E(c) is th e correlation energy). These results are compared with previous theore tical studies.