Charge separation effects at the solid-vacuum interface and ion acceleration with two electron populations

The electrostatic field at the solid-vacuum interface produced by two equilibrium electron populations with different temperatures is analytically calculated and investigated in terms of plasma parameters. The hot and the cold electron populations represent the laser accelerated electrons (typical energy of a few MeV), and the ambient electrons carrying the return current and heated due to the finite resistivity of the solid target. In the frame of this model, the ion acceleration process in laser-solid experiments is discussed. It is compared with the numerical results obtained by using a Boltzmann-Vlasov-Poisson model of ion acceleration.