Abstract

Now many laboratories pay a great attention to investigation of ultrashort laser pulse-matter interaction. We consider this interaction with condenced targets in vacuum. In this paper the results of absorption and conversion efficiency into X-ray are presented for a broad range of experimental parameters. The situation is studied when the contrast of laser pulse is sufficiently high. We have developed a simulation code for investigation of this interaction by the solution of Vlasov-Fokker-Planck equation for electron distribution function. Our study of heating process of dense plasma predicts high heating rate of electrons due to heat conductivity inhibition in the regime of anomal skin effect. The most common regim of the normal skin effect with continuous density profile at the plasma-vacuum boundary has been studied via numerical simulations, using our code. We have presented the numerical results and the approximate analytical solutions of the P-polarized radiation absorption problem with the parameters of extinguishing and density lying in sufficiently broad ranges. Our results predict absorption efficiency values, which are in agreement with our and another numerical data and experimental results too. We include full radiation terms (bremsstrahlung, recombination and line mechanisms) in the description of the decay phase high dense plasma targets. The hydrodynamic simulations with radiation transport are conducted to study the X-ray emmission and plasma cooling after the end of the laser pulse. The conversion efficiency into X-rays is shown to fall with laser intensity for light target materials in conditions, when invers bremsstrahlung absorption is dominant. On the other hand, when anomalous absorption prevails and havy target material is used, the conversion efficiency increases with laser intensity.

© 1994 Optical Society of America