The Investigation Of Controlling Of Photoelectron Momentum Distribution Of He⁺ And Non-Sequential Double Ionization Of Xe Under Intensive Laser Pulses

With the rapid development of laser technology,the method of using strong laser field to ionize atoms and molecules to explore the internal structure and electron dynamics of atoms and molecules has been widely used.In recent years,the ionization of atoms and molecules in the laser field has been studied by using the linearly polarized laser field and the circularly polarized laser field.By analyzing the photoelectron momentum distribution(PMD)obtained by the ionization of atoms and molecules in a strong laser field,a lot of information about the movement of ionized electrons in the laser field can be obtained.The ionization of atoms and molecules in strong fields produces various physical phenomena.Non-sequential double ionization(NSDI)has attracted extensive attention in the scientific community,which is important for understanding the effect of the ionization of atoms and molecules in strong fields.We theoretically investigate the PMD in the counter-rotating elliptically polarized laser field by solving the two-dimensional time-dependent Schr?dinger equation of He⁺.Vortex interference patterns in PMD are sensitive to different laser parameters.We illustrate the influence of time delay and ellipticity on PMD.To investigate the effect of the time delay of the two laser pulses on the vortex structure in the PMD,we calculate the vortex structure in the PMD generated by He⁺single-photon ionization at three kinds of time delays.The PMD have a double-leaf vortex structure and the vortex arms become longer and thinner with the increase of time delay.We explain this phenomenon with Attosecond Perturbation Ionization Theory.In the laser field with the same time delay,the larger the ellipticity,the longer the vortex arms generated by the ionization of He⁺by the laser pulse.The vortex structure in the PMD obtained by the ionization of He⁺under laser pulses with different ellipticities presents a complex state under the combined action of the circularly polarized laser pulse and the linearly polarized laser pulse.The vortex arms produced by the multi-photon ionization of He⁺in the elliptically polarized laser field have obvious intensity changes.When the time delay and ellipticity decrease,the strength of the two vortex arms in the PMD significantly weakens or even disappears.Because the separation of adjacent vortex arms can reflect the electron ionization time interval,when the vortex arms disappear,the electron ionization time doubles.Therefore,the electron ionization time can be controlled by adjusting the time delay and ellipsometry in the elliptically polarized laser field.Furthermore,we investigate the effect of phase on the PMDs.The electron vortices in the PMDs have a symmetrical structure when the relative phase of the two PMDs is?.For single-and two-photon ionization,we also demonstrate the influences of wavelength on the number of arms of vortices.The number of vortex arms is equal to the number of the photoelectrons that are absorbed in ionization.By partially overlapping linearly polarized laser pulses and circularly polarized laser pulses to construct a compound laser field with time-dependent ellipticity.The regulation of the ionization channel of the NSDI of Xe atoms by the time delay of the composite laser field is investigated.The overlap of the two laser beams in varied time delays is different.The electrons are ionized by the linearly polarized laser,and the ionized electrons are laterally controlled by the delayed circularly polarized laser.Adjusting the time delay between laser pulses can control the number of electrons of Xe returns before NSDI collisions.The drift time of ionized electrons can determine the main ionization channel of double ionized electrons,and the time delay of the recombination field can be adjusted to control the drift time distribution of ionized electrons.By tracing the history of the recollision trajectories,the regulation principle of the time delay in the compound field on the NSDI ionization channel is explained.