摘要： We present a numerical study of the effect of the laser spot size of a circularly polarized laser beam on the energy of quasi-monoenergetic protons in laser proton acceleration using a thin carbon-hydrogen foil. The used proton acceleration scheme is a combination of laser radiation pressure and shielded Coulomb repulsion due to the carbon ions. We observe that the spot size plays a crucial role in determining the net charge of the electron-shielded carbon ion foil and consequently the efficiency of proton acceleration. Using a laser pulse with fixed input energy and pulse length impinging on a carbon-hydrogen foil, a laser beam with smaller spot sizes can generate higher energy but fewer quasi-monoenergetic protons. We studied the scaling of the proton energy with respect to the laser spot size and obtained an optimal spot size for maximum proton energy flux. Using the optimal spot size, we can generate an 80 MeV quasi-monoenergetic proton beam containing more than 108 protons using a laser beam with power 250 TW and energy 10 J and a target of thickness 0.15 wavelength and 49 critical density made of 90% carbon and 10% hydrogen. 出版者： Melville: American Institute of Physics 出版日期： 2014-06-01 出處： Physics of plasmas, 2014-06, Vol.21 (6) 資源來源： AIP Publishing 版權： AIP Publishing LLC 版權： 2014 AIP Publishing LLC. 識別號： ISSN: 1070-664X 識別號： EISSN: 1089-7674 識別號： DOI: 10.1063/1.4882436 識別號： CODEN: PHPAEN
