High energy proton acceleration in interaction of short laser pulse with dense plasma target

The generation of high energy protons from the interaction of a short laser pulse with a dense plasma, accompanied by a preformed low density plasma, has been studied by particle-in-cell simulations. The proton acceleration toward the laser direction in the preformed plasma is characterized by a time-dependent model and the peak proton energy is given. The effect of electron recirculation on the rear side sheath acceleration is discussed and it is found that the peak proton energy increases in inverse proportion to the target thickness. These results shed light on the peak proton energy dependence on laser intensity, laser pulse length, and target thickness. Finally the optimal parameters of the laser pulse for large ion peak energy and conversion efficiency are discussed. (C) 2003 American Institute of Physics.