High-intensity laser-driven proton acceleration enhancement from hydrogen containing ultrathin targets

Laser driven proton acceleration experiments from micron and submicron thick targets using high intensity (2 × 10²¹ W/cm²), high contrast (10⁻¹⁵) laser pulses show an enhancement of maximum energy when hydrogen containing targets were used instead of non-hydrogen containing. In our experiments, using thin (<1μm) plastic foil targets resulted in maximum proton energies that were consistently 20%–100% higher than when equivalent thickness inorganic targets, including Si₃N₄ and Al, were used. Proton energies up to 20 MeV were measured with a flux of 10⁷ protons/MeV/sr.