Simulation of Proton Acceleration With Varying Laser Intensity in the Presence of Suprathermal Electrons

In the framework of high laser–plasma interaction, 1-D particle-in-cell (PIC) simulations are performed in order to optimize the role of electron suprathermality to generate high-quality proton beams useful for diverse applications, despite the presence of high nonlinear laser effects. For that, the electrons are supposed to obey the kappa distribution function discretized in the simulation code. Various characteristics of the proton beams, such as proton and electron densities, electric fields, front position, and energy spectra, have been analyzed as functions of electron suprathermality and laser amplitude. It is shown that, in the case of the presence of an important population of suprathermal electrons, the protons converge toward the same energy, leading to a quasi-monoenergetic beam and to good front position stability despite the presence of a large laser field. In addition, the two effects of electron suprathermality and laser intensity are added to enhance the proton acceleration. It turns out that in the analyzed range of laser intensities, the presence of the suprathermal electron population is beneficial for the proton acceleration process, which minimizes the nonlinear effects due to the laser field induced in high laser–plasma acceleration.