RESUMO
The interaction of a femtosecond relativistic intensity laser pulse with a grating of subwavelength periodicity was simulated numerically. Strong coherent emission at the wavelength of the grating period and its harmonics was seen, nearly parallel to the target surface, due to relativistic electron bunches emanating from each protuberance. Normal and oblique incidence (30 degrees ) gave rise to trains of attosecond pulses and an efficiency greater than 10;{-4} was obtained for the 24;{th} harmonic (lambda approximately 16.7 nm) . Similarity theory gives optimum conditions for harmonic emission.
RESUMO
A nonlocal model of electron heat flow in laser-heated plasmas taking into account the super-Gaussian deformation of the electron velocity distribution function by the laser heating was developed. Based on comparisons to Fokker-Planck simulations of hot spot heating, it performs better than previous models. The growth rate of thermal filamentation is considerably changed by this thermal conductivity modification. First results from a formula describing the isotropic component, f(0)(x,v), of the electron velocity distribution function as a spatial convolution over local Maxwellians are also presented.