2D modeling of field ionization role in ion acceleration from thin foils irradiated by laser pulse of 1021 W/cm2 intensity

When femto-second pulse of Ti-Sa laser with 10²¹ W/cm² intensity and 40 fs pulse duration interacts with 0.1 mum thickness aluminum foil, matter ionization is defined by electric field of the laser. The influence of field ionization on ion acceleration is studied with 2D hybrid code calculating fast particles by particle in cell method and thermal particles by approximation combining particle method and MHD approach. Results of the calculation are compared to the case, when plasma has initial state corresponding to temperature 100 eV. It is shown, that efficiency of energy transformation from laser field to electrons and ions is much higher when field ionization effect is taken into account. This leads to increasing of the depth of skin-layer and energy of electrons. Influence of Weibel instability development on magnetic field saturation and return current generation is studied. Calculations show that protons are accelerated due to the field of charge separation up to energies of 20-100 MeV in the case of field ionization that by an order exceeds the amount of ions in the case of initial plasma set.