Heating and ionization of metal clusters in the field of an intense femtosecond laser pulse

Inverse bremsstrahlung heating and thermal electron-impact ionization of a metal cluster are analyzed with account for the spatial structure of the electromagnetic field. It is shown that, for a femtosecond IR radiation pulse with an intensity of ∼1018 W/cm2 and for an iron cluster with an optimum radius of ∼25 nm, the electron temperature is higher than 1 keV. In this case, the L shell of the ions is highly stripped. The X-ray bremsstrahlung yield from clusters with a radius greater than the skin depth is estimated.