Efficient heating of near-surface plasmas with femtosecond laser pulses stimulated by nanoscale inhomogeneities

The interaction of intense (10¹⁶ - 10¹⁸ W cm^-2) ultrashort (50–200 fs) laser pulses with the dense plasmas produced at the surfaces of the porous target is numerically simulated by the particle-in-cell technique. Nanostructure-enhanced absorption of femtosecond pulses in high-porous (P>4) targets is demonstrated. We show that the presence of plasma inhomogeneities essentially alters the heating of plasma electrons and ions; in particular, it stimulates the significant increase in the mean energy and number of hot electrons. The numerical investigation of the dynamics of plasma electrons made it possible to reveal the physical mechanisms behind their heating in a porous medium.