The interaction of ultra-short intense laser with a thin foil has been studied by one- and two-dimensional particle simulations, which include the collisional absorption and the hard x-ray bremsstrahlung processes. The bremsstrahlung processes are modeled in a fully relativistic way in the frame work of quantum electrodynamics and integrated by the Monte Carlo method in particle-in-cell code. For carbon thin foils in which electron density is 200 times critical density, a laser pulse with an intensity greater than 10(18) W/cm(2) irradiates the foil normally to accelerate electrons on the surface along the laser propagation direction by the oscillating ponderomotive force. As a result, hard x rays over the range of 100 keV are emitted strongly toward the laser direction. The spectrum of the photon energy and scaling of the hard x-ray emission with respect to the various laser intensity are investigated by the newly developed simulation code. (C) 1998 American Institute of Physics. [S1070-664X(98)01612-7]. [References: 13]
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