The Dynamics of Dense Plasmas Produced by Ultra-Short Pulse Lasers

Abstract

The interaction of an ultra-short pulse high intensity laser with a solid target is of current interest because the resulting plasma is also solid density. Such a plasma might be a bright short pulse continuum x-ray source [1] to pump an x-ray laser or probe transient properties such as phase transitions or biological phenomena [2]. Recent experiments [3] have revealed that these plasmas are good continuum emitters and that the continuum x-ray duration is sub-picosecond (streak camera limited). The x-ray pulse width is primarily determined by the rate at which the electrons and the ionization stages cool from the diffusion of heat into the solid and the expansion of material into the vacuum. In the following we report the results of a one dimensional fluid code that models the interaction of an ultra-short laser pulse with a solid target of Aluminum. We describe the dynamics of the mass density, pressure, ionization and expansion velocity. In a related paper we discuss the effects of these quantities on the pulse width of continuum x-ray radiation generated by recombination [4].