Intensity Dependence of Coulomb-Repulsion Effect in Strong-Field Nonsequential Double Ionization

The nonsequential double ionization of the argon atom is studied in this article using an orthogonal two-color laser pulse with different intensities. The results demonstrate that electron correlation is strongly dependent on the relative phase of the laser pulses. We also observe that the recollision time remains constant when analyzing the nonsequential double ionization signal at the relative phase 0:6 pi. Meanwhile, the contribution of each returning bunch of the first ionized electron and the final electronelectron repulsion highly depends on the laser intensity. Coulomb repulsion is most pronounced at low and high laser intensities. However, at moderate laser intensities, it does not sufficiently affect the momentum distribution.