KINETIC TO THERMAL-ENERGY TRANSFER AND INTERPENETRATION IN THE COLLISION OF LASER-PRODUCED PLASMAS

An experimental and numerical analysis of the collision of two plasmas produced from laser-exploded Al/Al and Al/Mg pairs of foils is presen ted. Various imaging and spectroscopic x-ray techniques have been used to diagnose the collision over a broad range of intertarget distances and laser intensities. Ion temperatures in the 10 keV range have been measured from Doppler broadening. Electron temperatures and densities have been deduced from line ratios and interpenetration distances hav e been determined by the spatial extent of Mg and Al x-ray lines. Eule rian multifluid simulations have been developed and coupled to atomic physics postprocessing. The comparison of the measurements with these simulations shows that interpenetration prevails at large intertarget distances and high laser intensities; kinetic to thermal energy transf er then takes place on a similar to 200-mu m wide region and during si milar to 150 ps. (C) 1997 American Institute of Physics.