Effect of a short weak prepulse on laser-triggered front-surface heavy-ion acceleration

Abstract

A suppression of light-ion acceleration (from surface water contaminants) was observed when a moderate-intensity subpicosecond laser pulse was focused on a thick metal target. Simultaneously, an effective generation of high-energy multicharge ions of the target material (Fe) was experimentally observed. A numerical simulation based on the Boltzmann–Vlasov–Poisson model revealed that this is due to the very specific regime of cleaning contaminants from the target surface by the short weak prepulse preceding the main pulse by more than 10 ns and having an intensity below the surface breakdown threshold. Because this prepulse causes the contaminant layer to boil explosively, a low-density gap forms above the target surface. These conditions are consequently favorable for boosting the energy of heavy ions.