Ion acceleration during isothermal expansion of plasma slab into vacuum

The interaction of short intense laser pulses with solid targets allows record-breaking ion energies to be attained at the laboratory scale. Quasineutral plasma outflow and the regime of plasma expansion with charge separation effects in collisionless isothermal expansion of a semi-bounded plasma have been theoretically studied in great detail. However, at high electron energy (temperature) the model of semi-bounded plasma becomes inapplicable as far as the electron Debye length, $\lambda_{D_e}$ approaches the foil thickness, $L$. Also, analytically well studied regime of ion acceleration from plasma foil is the Coulomb explosion. Going beyond previous studies we have developed a theory of plasma slab expansion into a vacuum where the electrons follow Boltzmann distribution with an arbitrary temperature. The electron temperature, $T_e$, is a controlling parameter of our theory and matches laser intensity. By increasing $T_e$ ($0