A Theoretic Study On Some Basic Problems In The Process Of Intense Laser Plasmas Interaction

The study of intense laser pulse interact with plasmas is relevant to a wide range of important applications, and it tempted many people to explore it continually. With the development of study, the results from the study of the intense laser interact with the fully stripped plasmas can't meet the requirement of the exactitude physic of modern study. So the study of the intense laser interact with the partially stripped plasmas is very important.When an intense laser pulse propagating in the partially stripped plasmas, due to the shape of the atom (ion) with some unstripped hound electrons will change under the effect of the intense laser field, there will generate a nonlinear polarization of the partially stripped atom (ion), and a nonlinear polarization current come into being. Obviously, it is different from the fully stripped plasmas, and certainly, it will influence the interaction of the intense laser pulse and the plasmas, and the propagation characteristic will different from the laser in the fully stripped plasmas too.Whereas, it is very difficult to solve the nonlinear response problem of the atom accurately, especially, the nonlinear susceptibility of the medium cannot be obtained. So, in this paper, we presented a model aimed at the linear polarized laser field. In this model, the shape of electron cloud is described as a spheroid, and takes no account of the further ionization of the bound electrons and combination of an ion with free electrons. From this model, the linear and nonlinear susceptibility can be obtained self-consistently. At low laser field limit, these results are consistent with the results that obtained from the traditional non-harmonic oscillator model and the correlative inherent frequency of the oscillator and the nonlinear coefficient can also be obtained.Using the analytical results of the first and the third susceptibility derived from this model, we analyzed the variety of the refraction index yvhen the intense laser propagating in the partially stripped plasmas, and based on the variety of the refraction index, we have discussed the laser self-focusing and the formation of plasma channel in the process of propagation.Take account of the strong ponderomotive force from the ultra-short intense laser pulse, the effect of ponderomotive on the radiation of bound electrons in the intense laser pulse field is also discussed in this paper. All these results provided a theoretic reference in the basic study of intense laser pulse interact yvith partially stripped plasmas.