Proton Acceleration by High Intensity Laser Field: Self-Similarity Description

This paper studies the specific features of energy and angular distribution of protons accelerated by high intensity ultrashort laser pulse from a dense target. Production and acceleration of particle beams by ultrashort laser pulses with light intensities of order of 10 W/cm and higher is interesting both from the theoretical point of view and for practical applications, e.g., development of compact sources of quasimonoenergetic quasimonodirectional particle beams. The self-similarity approach [1-3] developed for relativistically invariant description of multiparticle interaction in nuclear physics was used for description of the process “hardness” [4]. This method was successfully applied to the problem of positron production in collective photon field-matter interaction [5]. Here, the developed approach is applied for the analysis of energy and angular spectra of proton beams produced in the target interaction with high intensity laser fields. The four-momentum conservation law written for the group of “coherent photons” (considered as a “big photon”) and the proton in the initial and final states is used to obtain the proton cross section distributions,