VORTEX DYNAMICS IN MAGNETIZED PLASMAS

Low frequency dynamics of electrostatic fluctuations in strongly magne tized plasmas have been studied. It was found that perturbations in de nsity and potential can be very localized, indicating the applicabilit y of an approximate description based on a finite number of vortices. A model based on a few isolated vortical structures is discussed, with particular attention to vortex collapse, where three vortices merge t ogether within a finite time, or to the converse process, i.e. a vorte x explosion. Details of these particular types of vortex dynamics depe nd on the actual model used for describing the electrons, the presence of a Debye shielding in particular. A ''boomerang''-type of evolution was found where three shielded vortices expand initially, just as the ir unshielded counterparts, but eventually the expansion is arrested, and they start converging to collapse ultimately. The study is extende d by a numerical simulation where the point model is relaxed to a cont inuous, but localized, vorticity distribution with finite size vortice s.