Quasi monoenergetic proton beams from a laser plasma accelerator using microstructured, polymer coated targets

A laser plasma accelerator based on the mechanism of Target Normal Sheath Acceleration (TNSA) was used to generate a quasi monoenergetic proton beam. The protons were accelerated from polymer dots on the backside of a thin Titanium foil. The proton spectra exhibit peaks around E = 1.2 MeV, with energy spread of ΔE/E = 25 %. Our experimental results are well reproduced by 2D-PIC-simulations, which also show that for intensities around 10 21 W/cm 2 low-emittance monoenergetic proton beams with an energy of nearly