Dipole and monopole vortices in nonlinear drift waves

The problems of existence and stability of drift vortices in plasmas with density and temperature inhomogeneities are studied analytically and numerically. It is shown that basically two space scales are involved: (i) the ion Larmor radius at the electron temperature, where dipolar vortices exist, and (ii) a longer space scale on which monopolar vortices are possible. The latter are shown to survive finite disturbances. A Liapunov functional for structural stability is presented. The analytical predictions are verified by a 2D numerical simulation.