SELF-FIELD EFFECTS IN 2-DIMENSIONAL NB JOSEPHSON-JUNCTION ARRAYS

We have measured two-dimensional niobium Josephson junction arrays in which self induced fields are important. We find an increase of the de pinning current when lambda(perpendicular to), the penetration depth i n the array, is of the order of one. There is evidence for a destructi on of commensurate vortex states in the arrays as the depinning curren t becomes almost independent of the applied magnetic field. Our data a lso show that self-field effects change the array flux-flow dynamics a nd decrease the effective array viscosity.