  The interaction of high intensity laser radiation with underdense plasma may
lead to the formation of electron vortices. Though being quasistationary on an
electron timescales, these structures tend to expand on a proton timescale due
to Coloumb repulsion of ions. Using a simple analytical model of a stationary
vortex as initial condition, 2D PIC simulations are performed. A number of
effects are observed such as vortex boundary field intensification, multistream
instabilities at the vortex boundary, and bending of the vortex boundary with
the subsequent transformation into smaller electron vortices.
