Influence of target material on structure of the plasma outflow produced by a partly defocused laser beam

This paper is aimed at the explanation of mechanisms responsible for plasma jet formation: the radiative cooling of ablative plasma and the influence of target irradiation geometry. The experiment was carried out with the Prague Asterix Laser System (PALS) iodine laser. A three-frame laser interferometer and an x-ray streak camera were used as two main diagnostic tools. These investigations have shown that the geometry of target irradiation is crucial, an annular target irradiation being necessary for plasma jet formation. Thus the role of radiative cooling in the plasma jet forming seems to be negligible.