For a model atom with the $p^3$ valence shell we construct consistent three- and two-active-electron models enabling their direct comparison. Within these models, we study the influence of the third active electron on the double-ionization yield in strong femtosecond laser fields. We reveal proportionality between double-ionization signals obtained with both models in the field intensity region where nonsequential ionization dominates. We derive analytically a correspondence rule connecting the double-ionization yields obtained within the three- and two-active-electron models.

• Received 12 March 2020
• Revised 20 April 2020
• Accepted 19 May 2020

DOI:https://doi.org/10.1103/PhysRevA.101.063402