Current gradient-driven linear and nonlinear electromagnetic waves in a magnetized electron-positron plasma

Abstract

A set of coupled nonlinear differential equations which govern the dynamics of finite amplitude electromagnetic waves in the presence of an external current gradient in a magnetized electron-positron plasma has been derived. It is shown that the current gradient can make shear Alfven-like waves unstable. A quasi-stationary solution of the mode-coupling equations is the well-localized dipole vortex. Application of our results to plasma transport in the pulsar magnetosphere is briefly discussed.