Concerning the maximum energy of ions accelerated at the front of a relativistic electron cloud expanding into vacuum

Bulanov, S. V.*; Esirkepov, T. Z.; Koga, J. K.; Tajima, Toshiki; Farina, D.*

With the use of the 2D PIC simulations it is demonstrated the regimes of the interaction of the high intensity laser radiation with plasmas when the energy of fast ions is well above the electron energy. This phenomenon is explained within the framework of the theoretical model, which describes the ion motion in the electric field formed inside relativistic electron cloud expanding into a vacuum under the conditions of strong electric charge separation. The upper limit on the maximal energy of fast ions accelerated at the front of the relativistic electron cloud is found.