The Research And Design Of The SG－Ⅲ Thomson Scattering

The long-term goal of the Inertial Confinement Fusion（ICF）research is to madethe nuclear fusion controlled. Then the ideal energy would be provided for human.The current focus is the physical experiments. The comprehensive experiments anddecomposition experiments should be carried out then we can find out the laws ofeach physical processes. The premise for us to complete these physical experiments isthat we have good diagnostic equipment and diagnostic techniques. Thomsonscattering diagnostic is a very accurate and reliable method to diagnosis theparameters such as plasma electron temperature in Tomak device. Now thistechnology has been widely used at international inertial confinement fusion research.And different types of scattering system for measuring plasma electron temperatureand density are developed. With the development of the ICF research in domestic, theThomson scattering diagnostic system is needed for the measurement of plasmaparameters urgently.This paper focuses on establishing a Thomson scattering diagnostic imagingsystem used in “SG-Ⅲ”laser fusion facility prototype and some research on theprinciple of the Thomson scattering diagnostic imaging, optical system design,mechanical design of the system and instruments precision analysis. Main contentsas following:First, introduced the background of the subject, the background and significanceof the ICF research, the development of the ICF in domestic and international, thedevelopment of the Thomson scattering method to measure the plasma parameters. Especially, the using of the Thomson scattering optical system is introduced in detail.Second, the basic theory of the Thomson scattering is discussed, the causes of theThomson scattering spectrum are analyzed. Based on some related theories, weanalyses the relationship between the Thomson scattering spectrum and manyparameters of plasma. Further, we made the design targets for the Thomson scatteringdiagnostic imaging system.Third, we choose the double cassegrain system for the optical system designrequirements in the “SG-Ⅲ”Thomson scattering diagnostic imaging system. Theformer group is deformation cassegrain catadioptric system. The back group is thesecond cassegrain system which is placed inverted. The former group’s image plane isthe back group’s object plane. We calculate the light in detail; give the accurate valuefor the relative position of the optical components. The former and after opticalsystem aberration evaluation are carried out. The transmittance and tolerance of thesystem are analyzed, to achieve a rational allocation of tolerances. Mainly to solve theaperture problem in long-distance transmission, the difficult of long focal length lensprocessing and testing. We select an appropriate magnification in the image planebetween the former and the after. Then the shading ratio would be reduced in thesecond mirror. We add a transmission optical element near the first image plane forthe effective coupling of the two optical systems and et al.Forth, the mechanical system is designed for the Thomson scattering diagnosticoptical system. We design the cassegrain system structure for the former group andthe back group. The intermediate connection box structure is designed between theformer group and the back group. The movable cross reticle is designed in theintermediate connection box structure. It is convenient to aim each other between theformer group and the back group. Another, system works in a vacuum, we design avent hole with labyrinth cover. It is convenient for the gas emissions, at the same time,the stray light are eliminated.Fifth, the several factors that affect the system accuracy are analyzed and therelevant error is analyzed. Then we introduced the system’s experimental setup andthe relevant experimental results were obtained. After, the experimental results were analyzed.