Proton Acceleration due to Anisotropic Coulomb Explosion of a Double-Layer Target Irradiated by an Intense Laser Pulse

The ion acceleration by a hundred TW laser pulse irradiating a double-layer target is examined using three-dimensional particle-in-cell simulations. For a sufficiently high ion charge-to-mass ratio in the first layer of the target, a strongly inhomogeneous expansion of the first layer occurs due to its Coulomb explosion and the onset of the radiation pressure dominant acceleration regime. The time-varying electric potential of the inhomogeneously expanding ion cloud efficiently accelerates protons. Using the optimum material for the first layer and the optimum laser pulse incidence angle one can obtain a high-energy quasimonoenergetic proton beam.