Spiral pulse generation and subsequent ion acceleration via ultra-thin foil and circularly polarized laser pulse

Abstract

The interaction of high-intensity PW-class laser pulses with ultra-thin (tens of nm) foils provides interesting research conditions of high radiation pressure, strong self-generated magnetic fields and laser diffraction on generated aperture. When the laser pulse is transmitted through such a medium, its intensity profile can be enhanced, including generation of a steep-rising front, local intensity increase and improvement of its contrast. The use of a circularly polarized laser pulse is especially interesting in this setup, as the transmitted laser pulse can obtain a spiral-like intensity space profile. The structure is also transferred into the electron density profile of the expanded thin foil. In this work we compared the cases of linearly and circularly polarized laser pulse with the help of 3D particlein-cell simulations in interaction of an ultra-thin foil (plasma shutter) and the subsequent ion acceleration from the following target. The addition of the plasma shutter resulted in a generation of a spiral-like pulse in the case of circular polarization, significant reduction of the divergence of generated ion beam in the case of linear polarization and increase of maximal ion energy in both cases.