High-order harmonic generation from silver plasma

We report the studies of the generation of up to the 57th harmonic (λ=13.96nm) of a Ti:sapphire laser radiation from the prepulse produced silver plasma. The plateau pattern, analogous to those observed in gas-jet experiments for high harmonics, was investigated. The conversion efficiency for the harmonics in the plateau region was measured to be 8×10−6. The comparison of harmonics generated from silver and boron plumes showed a considerable difference in conversion efficiencies. The main contribution to the limitation of harmonic generation efficiency and cutoff energy was caused by self-defocusing of the fundamental beam.