Laser accelerated ions from near critical gaseous targets

Abstract

An intense laser pulse propagating through a near-critical density plasma is capable of generating a high peak current electron beam (~100kA) by means of a laser wakefield operating in the bubble regime. This beam drives surface currents on the sheath of the cavitation that produces large azithumal magnetic fields (~100 MG) and induces an on-axis electron current. These effects lead to a Z-pinch of the ambient plasma ions. Eventually the field confining the pinch relaxes and the ions explode radially due to self-repulsive forces. If this process occurs at a sharp exit gradient, the ions acquire some forward momentum consistent with the magnetic vortex acceleration mechanism. Fully 3D simulations indicate that the highest energy ions are emitted conically with a secondary lower energy ion beam accelerated on the axis.