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 10(18) and 10(22) W/cm(2), and the wavelength is 400 nm. The targets were foils of either aluminum at no rmal density, or in a few cases plastic (chemical formula CH) at a den sity of 1.1 g/cm(3), and varied from 20 to 4000 nm in thickness. The s imulation results show that at these intensities the absorption mechan ism for a normally incident pulse changes to a collisionless mechanism first proposed by kruer and Estabrook [W. L. Kruer and Ii. Estabrook, Phys. Fluids 28, 430 (1985)]. Use of a thin target ensures that the e nergy imparted to the electrons will be electrostatically transferred to the ions rather than transported for large distances into the targe t. (C) 1997 American Institute of Physics.