Vortex mass and viscosity in Josephson-junction arrays

We study, on the basis of the continuum limit of the standard model for Josephson-junction arrays, the motion of single vortices by directly deriving the equation of motion for the vortex coordinate. Thereby we confirm and extend recent studies by U. Geigenmüller et al. [this issue, Phys. Rev. B 47, 348 (1992)]. In addition, we discuss the case of a triangular lattice, where due to a lower potential barrier and a higher vortex mass, ballistic motion is more likely to be observable.