Investigation of the effect of target density profile in proton laser acceleration

Abstract

The common mechanism of proton laser acceleration is Target Normal Sheath acceleration. This study investigates the geometry of the aluminum target used in high-intensity laser pulse interaction with plasma. The target with an exponential profile on the front and back sides and with different scale lengths from 0 to 0.85 μm is used as an input to the two-dimensional particle simulation code. The results of their proton energy distribution have been compared. It was found that proton energy decreased with smooth changes behind the target. This is due to the reduction in the electrostatic field amplitude behind the target. In addition, there is a threshold scale length (here 67/0 μm), after which the proton energy does not change with the increase of this quantity and the energy distribution of the proton beam almost overlaps. The transverse laser field emission and the same electron energy distribution were also observed for two targets with zero and 0.67 μm scale lengths.

Keywords

• proton cut off energy
• laser acceleration of proton
• rear target profile