A high-energy, high-yield proton beam with a good homogeneous profile has been generated from a nanosphere target irradiated by a short (30-fs), intense (7 × 10 20 W=cm 2) laser pulse. A maximum proton energy of 30 MeV has been observed with a high proton number of 7 × 10 10 in the energy range 5-30 MeV. A homogeneous spatial profile with a uniformity (standard deviation from an average value within 85% beam area) of 15% is observed with the nanosphere dielectric target. Particle-in-cell simulations show the enhancement of proton cutoff energy and proton number with the nanosphere target and reveal that the homogeneous beam profile is related with a broadened angular distribution of hot electrons, which is initiated by the nanosphere structure. The homogeneous spatial properties obtained with the nanosphere target will be advantageous in developing laser-driven proton sources for practical applications in which high-quality beams are required.

No abstract

No abstract

No abstract

No abstract