IVcurves of long annular Josephson junctions (circumference much larger than the Josephson penetration depth) have been investigated numerically. It is concluded that an experiment on such a system is preferable to the usual linear geometries and will allow a study both of the undisturbed motion of a fluxon, and the fluxon‐antifluxon collision process. The simulations show that the fluxon‐antifluxon collisions generate long wavelength plasma oscillations which may give rise to fine structure in theIVcurves.