Dynamic modulation of multiple collision in atomic nonsequential double ionization by two-color circularly polarized laser pulses

Using a three-dimensional classical ensemble model (CEM), the dynamics of recollisions in strong-field nonsequential double ionization (NSDI) of argon atoms induced by counter-rotating two-color circularly polarized (TCCP) laser pulses are explored. Numerical results reveal that both the recollision excitation with subsequent ionization (RESI) and the recollision-impact ionization (RII) process exist in the multiple collision ionization event. We discover that the distribution of transferred energy during recollision is related to travel time, which can be regulated by the amplitude ratio. Statistical analysis of tunneling electron trajectories reveals that the motion of tunneling electrons can be controlled on the sub-femtosecond scale. Furthermore, the emission angle between the two electrons is jointly regulated by both the amplitude ratio and the recollision frequency, while the angle formed by the laser-induced force and the tunneling electron's instantaneous momentum at the moment of collision critically determines the recollision count.