Electrostatic shock waves driven by electron vortices in laser–plasma interactions

Abstract

Nonlinear structures such as shock waves and vortices widely exist in nature and universe. They have also been separately observed in laser plasma interaction. We show for the first time that two perpendicularly propagated collisionless electrostatic shock waves (CESs) can be excited by a moving electron vortex (EV). The latter are driven by an ultra-short intense laser pulse propagating through a sandwich nonuniform underdense plasma slab and are found to move perpendicularly to the density gradient. Two CESs are observed on both sides of the passing route of the EVs. The left side CES is induced by a high density electron layer which originates from the vortex front and is compressed and accelerated during the EV motion. The right side CES is induced by supersonic ions accelerated by the EVs directly. Ion acceleration by such CESs along the directions perpendicular to the vortex propagation is also observed. This study reveals the transformation of nonlinear structures and provides new routes for laser energy dissipation in plasmas.