Motion of extended vortices in an inhomogeneous pure electron plasma

The motion of extended vortices in a pure electron plasma with an inhomogen eous, centrally peaked, density in a Penning-Malmberg trap is studied by me ans of a two-dimensional electrostatic Eulerian code that solves the evolut ion equation for the electron distribution function in the guiding center a pproximation, coupled to the Poisson equation for the electrostatic potenti al. Vortices corresponding to electron density clumps propagate inward, as discussed in a recently proposed model for the case of point vortices, and carry inward both high and low density plasma. New, long-lived, structures consisting of a higher and of a lower density vortex pair are formed in the presence of a small amount of vorticity reconnection. (C) 2000 American In stitute of Physics. [S1070-664X(00)03407-8].