The Theoretical Study Of Non-sequential Double Ionization Of Argon Under Orthogonally Polarized Two-color Laser Fields

With the development of laser pulse technology,the exploration of strong field double ionization has been one of the important subjects of strong field physics.Among them,non-sequential double ionization of atoms in intense laser field has drawn wide attention.It not only reflects the interaction between electron and laser field,but also reveals the strong correlation between electrons.And it?s one of the most common multi-electron interactions in nature.In order to study the dynamic process and physical mechanism in NSDI,we need to explore the influence of various factors on NSDI.In addition,orthogonally polarized two-color laser fields is an important tool to know and control NSDI.The influence of all kinds of laser and adjustable parameters on the correlation between electrons is worth studying.In this paper,an orthogonally polarized two-color laser fields is used to explore NSDI of argon atoms,and we hope it can reveal the dynamic process of non-sequential double ionization and associated behavior between two electrons.At the same time,this thesis investigates the control of the laser field on NSDI.In order to finish the theoretical studies,a variety of calculation methods is been invented.They can accord well with the experimental results,which include the semi-classical theory method,the classical theory method and the method of solving the quantum equations.Among them,the classical theory method is widely used because of its high efficiency and convenience.In this paper,classical model is adopted to explore the electron correlations in non-sequential double ionization.First of all,we apply the classical ensemble method to investigate the effect of many-circle orthogonally polarized two-color laser fields on non-sequential double ionization of argon atoms.Through the analysis of double ionization yield versus laser intensity with different field intensity ratio,we find that relative phase of the laser field has less influence on the double ionization yield when field intensity ratio is relatively small.And when field intensity ratio increases,the effect of relative phase on double ionization yield is not negligible.The relative phase of electric field has great effect on the correlation between electrons because when the second laser field is equivalent to the first laser intensity,the relative phase determines the waveform of the laser field to a greater extent.By simulating waveform of laser field and ion momentum distribution,we find that the ionization of double electrons is mainly affected by relative phase of electric field and field intensity ratio.Secondly,non-sequential double ionization of argon atoms is investigated under few-circle orthogonally polarized two-color laser fields by classical theory method.We calculate the CEP-dependent double ionization yield versus laser intensity,and observe that the CEP-dependent mechanisms will generate or disappear when we change relative phase.And then,we simulate the time evolution of the distribution of the electron energy,the repulsion energy between double-ionized electrons to analyze NSDI channels versus different relative phase.As the ionization channel is clear,the CEP-dependent mechanisms is also more obvious.Next,we separate it into RII and RESI channels.By simulating ratio of the two channels versus CEP,we find some interesting results.The channel of RII or RESI could be appropriately turned off or turned on under the control of carrier envelope phase.And the more complex the ionization channel is,the less the double ionization yield versus laser intensity is affected by CEP.Respectively,and it is contrary to the clear ionization channel.