Theoretical Study On Dynamics Of Laser-Assisted Proton-Hydrogen Atom Collision

Particle collision is one of the important ways to study the interaction of matter and laser is an important tool for manipulating matter.Laser technology has been continuously reformed since the 1960s.With the emergence of chirped pulse amplification technology,the peak intensity of laser pulse has been greatly improved,reaching and exceeding the terawatt(10¹²W/cm²)magnitude,and the pulse duration has been reduced to the femtosecond(10¹⁵s)magnitude.The electric field of such a strong laser is comparable to the Coulomb effect of the nucleus on the electron,and the pulse length is close to the collision time.Therefore,the collision process of particles can be greatly influenced and regulated by ultrafast laser.The collision between proton and hydrogen atom is the simplest particle collision process.It can provide important prototypes and mechanisms for various complex collision phenomena.Therefore,in this paper,the time-dependent Schr(?)dinger equation is solved by numerical method,the collision process between proton and ground state hydrogen atom assisted by strong laser is simulated,and the collision dynamic is deeply studied.The work is mainly carried out in the following two aspects:The first part,we systematically discuss the proton-hydrogen collision process assisted by circularly polarized laser with different laser parameters and collision parameters.Firstly we systematically analyze the parameters that give significant impact on the collision process.For example,laser frequency and the velocity of proton incidence.The results show that the probability of electron capture is highly dependent on the laser phase when the laser frequency is low.At this time,the probability of electron capture appears the sub-maximum value and the maximum value at 90 and 270 degrees,and the minimum value at 0 and 180 degrees,respectively.The reason is related to the interaction time between particles.However,in dependence of electron capture on laser frequency,electron capture is obviously enhanced at some specific frequencies.Because of the addition of laser,at the appropriate laser frequency,there is a single photon or two photon resonance between the ground state and the excited state.The excited electrons are more easily captured by incident protons,thus increasing the yield of electron capture.In addition,there is obvious circular dichroism in the probability of electron capture at lower laser frequencies,but for higher laser frequency,this circular dichroism effect weakens or fails,the resonance enhanced electron capture and ionization is the origin of these phenomena.And the results show that the dependence of electron capture probability on phase of the laser changes with the increase of proton incidence velocity,and the structure changes gradually from double peak to single peak.This is caused by the fact that the time of particle interaction is affected by both the laser and the velocity of proton incidence.By using the"rigid sphere model",we find the law of the velocity proton incidence corresponding to the peak position of the probability of electron capture when the collision parameter is less than 4a.u.and the laser phase is 270 degrees,and predict the proton incidence velocity of its peak capture probability.Then,we further study the collision process between proton and ground state hydrogen atom assisted by linearly polarized laser.The results show that under different collision parameters,the probability of electron capture is obviously dependent on the phase of laser when laser frequency is low.(other parameters have been fixed).The Angle between the the x direction and the direction of polarization of a linearly polarized laser has a strong effect on this dependence.For higher laser frequencies,the electron capture probability increases monotonically as the laser frequency increases due to the competition between electron capture and laser-induced ionization.