Classical Effects of Carrier--Envelope Phase on Nonsequential Double Ionization

A classical microcanonical 1+1-dimensional model is used to investigate the ion momentum distributions in nonsequential double ionization with linearlypolarized few-cycle pulses. We find that the ion momentum distribution has a strong dependence on the carrier--envelope phase of the few-cycle pulse, which is consistent with the experimental results qualitatively. Back analysis shows that the ionization probability of the first electron at different phases and its returning kinetic energy play the main role on the ion momentum distributions.