Ion acoustic and drift wave vortices in electron-positron-ion plasmas

It is shown that two-dimensional large amplitude ion acoustic waves can give rise to dipolar vortex structures in magnetized homogeneous electron-positron-ion plasmas. In nonuniform plasmas they can couple with drift waves and similar structures can again be produced. A comparison with earlier works on pulse-like soliton formation of these waves in magnetized and unmagnetized electron-positron-ion plasmas is also presented. (C) 2003 American Institute of Physics.