One-dimensional simulations of ultrashort intense laser pulses on solid-density targets

Presented are simulations in one dimension of laser pulses with a pre-ionized thin target. The duration of the laser pulse is between 10 and 200 fs, the laser power is between 1018 and 1022 W/cm2, and the wavelength is 400 nm. The targets were foils of either aluminum at normal density, or in a few cases plastic (chemical formula CH) at a density of 1.1 g/cm3, and varied from 20 to 4000 nm in thickness. The simulation results show that at these intensities the absorption mechanism for a normally incident pulse changes to a collisionless mechanism first proposed by Kruer and Estabrook [W. L. Kruer and K. Estabrook, Phys. Fluids 28, 430 (1985)]. Use of a thin target ensures that the energy imparted to the electrons will be electrostatically transferred to the ions rather than transported for large distances into the target. copyright 1997 American Institute of Physics