Characteristics and evolution of plasma-jet-like structures in line-focused laser-produced plasmas

We have used five-frame photography to investigate plasma-jet formation and its evolution in line-focused laser-produced plasmas. Small-scale plasma jets have been observed in low-Z and high-Z plasmas. We have also observed relatively large-scale plasma jets, which are similar in appearance to ``tips of oxhorns'' and always appear at the boundaries between hot plasma and cold target material or between two different-Z (e.g., high-Z and low-Z) plasmas. It is also shown that the plasma-jet structure is more pronounced for the short-wavelength-laser--irradiated targets. The causes of plasma jets and their influence on x-ray--laser schemes using a line-focused laser-produced plasma as a gain medium are discussed.