Figure 1: Intensity of harmonic 23 (H23) from argon gas versus intensity of the driving laser for two optimized cases of the driving laser intensity a) 0.6 mJ (triangles) and b) 2.2 mJ (circles). The symbols show the experimental data and the lines show the fit. The inset shows the HHG spectrum for two optimized cases when a 2 mJ laser pulse is applied.