The Non-sequential Double Ionization Of Argon In Two-color Laser Fields

The ionization is one of the most fundamental and significant physical phenomena during the interaction of laser field and matter.Due to the complicated ultrafast dynamic process between the electron and laser field,electronic interaction and between electron and nucleus in the time scale of femtosecond and even sub-femtosecond,the double ionization process,especially,the non-sequential double ionization induced by an intense laser field has become a typical methodology to investigate the complex dynamics of multi-electron correlation process.In past several decades,the nonsequential double ionization dynamics has been studied intensively and extensively both in theoretical calculation and experiment.In this thesis,based on the full classical ensemble method,the ultrafast dynamics of two correlated electrons produced during the non-sequential double ionization of Ar atom in two-color laser fields has been explored.The details as follow,(1)Using soft core potential classical ensemble model,the non-sequential double ionization process of argon atom in the 800 nm and 400 nm orthogonal two-color fields has been studied.We theoretically analyzed the relationship between the yield of nonsequential double ionization and laser field parameters,such as the laser intensity,the strength ratio of two-color fields and the relative phase of two pulses.By analyzing the kinetic energy time evolution of two electrons and the relationship between the collision time and ionization delay time,it is proposed that the electronic wave packets with different travel time demonstrate nearly opposite response of electron collision probability to relative phase.Moreover,by adjusting the intensity and the relative phase of two pulses,the reaction mechanism of non-sequential double ionization is realized.(2)Non-sequential double ionization process of Ar atom in the 800 nm and 400 nm two-color counter rotating circular polarization fields has been studied under the classical ensemble model.The dependence of argon ionization mechanism,double ionization quantum yield and non-sequential double ionization yield on the laser intensity,laser fields strength ratio,relative phase and pulse width of two pulses is calculated and analyzed,detailedly.We simulated the time evolution spectrum of kinetic energy and interaction energy of double electrons,and two different nonsequential double ionization mechanisms have been revealed.The influence of the electronic collision energy for different non-sequential double ionization processes has also been discussed.