| Inertial Confinement Fusion (ICF) which is one of the common methods of controlling nuclear fusion plays more important role in the development of new energy resources and national defense science. ICF laser driver consists of many amplifiers. In new-model laser driver, the main amplifier which commonly has many disk amplifier mediums is multi-pass amplifier system. To avoid element damage due to super-high optical power, it is very significant to research the characteristics of optical beam passing through cascade nonlinear elements for ICF driver's design and manufacture.The thesis consists of two parts.In the first part, the expression of Gaussian beam intensity after passing through cascade nonlinear element in arbitrary location is derived firstly by using Fresnel diffraction principle and Fourier transform method. Besides the theoretical analysis, the numerical result is introduced, and the difference between theoretical and numerical is analyzed. After this, the corresponding relations with the optical beam peak intensity, the peak power location, beam width and modulation factor in cascade elements have been studied, and then, the effect rule on the optical beam transmission characteristics induced by the space between nonlinear components has been discussed. Above studies indicate that the nonlinear element should keep away from peak intensity of optical beam by all means. It is necessary to optimize the space between nonlinear elements for avoiding element damage in practical application.In the second part, the formation of the "hot image" has been studied by numerical simulation. The variation effect of hot-image is researched. Then, by analyzing the effect of diffraction beam size and space between mediums to peak intensity, the regulation of the intensity of the "hot image" with different space between mediums has been indicated. It is shown that the intensity of the "hot image" is independent of the distance between modulate plane and input plane of... |
PDF Full Text Request