VORTEX RING RECONNECTION IN LASER–MATTER INTERACTIONS

Abstract

Laser-induced microscale vortex rings have been generated on a vaporizing tantalum surface, and their reconnection was studied in the presence of the shock waves on the nanosecond (ns) time scale. A reach spectrum of the ring structures was obtained, some of which have been observed for the first time. Qualitatively, three classes of interactions were distinguished, on the basis of relative relation between the shock momentum PSand momentum of the circulating fluid PC: interactions in the presence of low-momentum shock waves (PS<PC); interactions in the presence of the shock waves with momentum comparable to the momentum of a circulating fluid (PS≈PC); and interactions in the presence of the shock waves of momentum larger than momentum of the circulating fluid (PS>PC). A matrix formalism was introduced for description of the reconnection process which assumes the reconnection as the transition between various states, and which automatically gives the time ordering of the processes, as well as the degeneracy of the states.