Strong-field multiple ionization of krypton

We have investigated the multiple ion yields of Kr, up to ${\mathrm{Kr}}^{4+}$ as a function of the field intensity, that are measured using a linearly polarized short-pulsed Ti:sapphire laser of $\lambda =800\mathrm{}\mathrm{nm}$ in the range of up to mid-${10}^{15}{\mathrm{W}/\mathrm{c}\mathrm{m}}^2,$ within an S-matrix model for nonsequential multiple ionization. Experimental data and theoretical predictions are in good agreement and the influence of different nonsequential channels on the measured ion yields are analyzed.