A new accelerated mechanism of protons in high power laser-plasma

In order to study effect of Compton scattering on protons accelerated along the normal direction of the target back side in the plasma,based on the model of multi-photon nonlinear Compton scattering and plasma particle-in cell simulation,the accelerated protons were analyzed and simulated,and a new mechanism of protons accelerated by the electrostatic field formed by incident laser and Compton scattering on the plasma face was put forward,then some important data were given out.The results show that the energetic electron numbers induced by Compton scattering in plasma are increased so that the electrostatic field on the target face of the energetic electrons is increased,and higher accelerated energy is absorbed by the protons.The proton gets the accelerated energy from the plasma of the gradual density scale length by Compton scattering higher than the energy getting from the plasma of the steep density scale length,and the key cause is that the effect of the electrostatic field increased by Compton scattering effectively compensates the loss energy of the electron in the transporting energy to the plasma as the increasing of the laser modulation instability taking place under Compton scattering.Therefore,it is perfect to accelerate protons with plasma of the gradual density scale length under Compton scattering.