Toward high-energy laser-driven ion beams: Nanostructured double-layer targets

The development of novel target concepts is crucial to make laser-driven acceleration of ion beams suitable for applications. We tested double-layer targets formed of an ultralow density nanostructured carbon layer (~7 mg/cm³, 8--12 μm--thick) deposited on a μm--thick solid Al foil. A systematic increase in the total number of the accelerated ions (protons and C⁶⁺) as well as enhancement of both their maximum and average energies was observed with respect to bare solid foil targets. Maximum proton energies up to 30 MeV were recorded. Dedicated three-dimensional particle-in-cell simulations were in remarkable agreement with the experimental results, giving clear indication of the role played by the target nanostructures in the interaction process.