Cross sections for simultaneous ionization/excitation of argon

Optical emissions from $3p^44p$ argon ion levels (420-490~nm) are widely used in plasma diagnostics. Cross sections for electron-impact from the ground state have been studied extensively since the 1960's for levels involved in argon-ion laser emissions. Much less work, however, has been performed on measuring cross sections for other excited levels. We present measurements for simultaneous ionization/excitation cross sections into virtually all of the levels of the $3p^44p$, $3p^44d$, and $3p^45s$ configurations, and a number of additional higher levels. Emission cross sections from 300-900~nm were measured using a monochromator/PMT combination, whereas near-IR transitions in the range 850-1500~nm were measured using a FTS/Ge detector combination.