Study On The Suppression Method Of Stimulated Rotation Raman Scattering Of High-power Laser Beams Of Long Distance

For the device of inertial confinement fusion (ICF), There will be a distancefor the fundamental frequency light to transmission from the main amplifier ofICF drivers to frequency converter, and the strong ultraviolet light that have beenfrequency converted also will Transmission a distance in air to reach the targetpills for targeting. However, there will be a lot of nonlinear effect when stronglaser beams transmission in the air for a long distance, stimulated rotationalRaman scattering (SRRS) is one of the biggest influence. SRRS effect will notonly make the beam quality of fundamental frequency light and frequencytripling light become poor, but also make significantly attenuation for the energyof Pump Light, produce a significant impact for the focus on targeting. At thesame time, the worse of beam quality for fundamental frequency light also leadto lower harmonic conversion efficiency, which affects the beam quality ofstrong ultraviolet laser. Therefore, there will be a great importance of theorystudy and practical application value to research on the suppression method foreffects of SRRS when strong laser making a long-term transmission in the air.Based on the basic principle and theory model for producing of SRRS andNumerical simulation of Growth process of it, this article analysis existingsuppression method for SRRS, and selected the Section of medium, Seed lightattenuation method and SSD method for further research. The growth rulesimulation of Stokes light by using different suppression method have been done,then calculate inhibition effect of various methods in the different conditions, itcan be concluded that: in Section of medium, using nitrogen and oxygen as atransmission medium, SRRS threshold distance will increase63.9%; in Seedlight attenuation method, theoretically threshold distance can increase100%atmost, but because the demand for the attenuation coefficient of attenuationcomponent is higher, it will generally increase20to40%threshold distanceaccording to different precision in the practical application; in SSD method, theinfluence of factors is relatively complex for SRRS, according to differentparameters selection, it can make the threshold value range increased about88%at most. At last, according to the calculation results, with the analysis ofadvantages and disadvantages of each method when using the China’s persuasiveIII high-power solid laser drive, a experiment scheme based on the Section of medium and a Alternative test plan based on Section of medium and Seed lightattenuation method are presented by comprehensive consideration of inhibitioneffect and feasibility.