Double, triple, and quadruple ionization of ﹩{\mathrm{Ar}}^{1+}﹩ forming ﹩{\mathrm{Ar}}^{3+}﹩, ﹩{\mathrm{Ar}}^{4+}﹩, and ﹩{\mathrm{Ar}}^{5+}﹩, respectively. The symbols show the data of Belic et al. (2010). For readability, the triple-ionization data were multiplied by a factor of 5 and the quadruple-ionization data by a factor of 20. Our cross sections using the semiempirical formulae are illustrated by the solid curves.