Characteristic Research Of Diffuser Panel In Near Backscatter Imaging System Based On ICF

The long term goal of laser inertial confinement fusion(ICF)is to solve the energy problem.The interaction between laser and plasma(LPI)is one of the important research topics in laser indirectly driven ICF research.According to relevant data show that the LPI process can produce a variety of physical mechanism,in which the stimulated scattering mechanism reduces the coupling efficiency of laser energy and target.In order to restrain the generation of backscattering mechanism,the integrated backscatter diagnosis system is established.The backscatter diagnosis consists of a full-aperture backscatter diagnosis system(FABS)and a near-back scattered light imaging diagnosis system(NBI).In NBI system,the way of collecting light is very important.In America,the research in the field of NBI started earlier than China,its representative of the NOVA device and NIF devices,NBI systems adopt diffuse reflection mode.In the domestic,earlier in the SG-III prototype,NBI system used glass spherical lens to receive light,through the spherical reflex method to the bull's-eye scattering of light emitted outside the target room for diagnosis,which is characterized by the image points in the optical axis,It is difficult to apply it in a large ICF device.Later,in the SG-III host,NBI system used metal ellipsoid lens to receive light,through the total reflection method of the bull's-eye scattering light emitted outside the target room for diagnosis,which is characterized by flexible optical arrangement,Compared to the previous glass spherical lens has significant advantages.With the deepening of ICF research in China and the establishment of larger ICF devices in the future,the irradiation intensity of near-scattered light will be improved,and the irradiation threshold of metal ellipsoid mirror will not meet the requirements.If it applied to NBI system of larger ICF device,it will be damaged by the light,which will affect the stability and accuracy of NBI system.In this paper,a series of preliminary studies have been carried out on the scheme of the near-scattered light in the larger ICF device.1)The proposal of new light receiving scheme in NBI system in the domesticWith the deepening research of ICF and the replacement of ICF devices,the new problems need to be solved,that is,radiation threshold of current domestic light receiving device is low,easy to be damaged.Therefore,a new method of collecting near-back scattered light using a diffuser panel is proposed.The panel's material has a higher radiation tolerance threshold.The proposed scheme compared with American,American scheme only has a certain reference value.Their application environment and requirements are different,they also have different application purposes and solve different specific problems.2)Characteristic Analysis of Diffuse Reflector in NBI SystemBased on the analysis of the application of the diffuse reflector plate,the characteristics of the diffuse reflector,which are the direction hemisphere reflectance,the bidirectional reflection distribution function,the surface uniformity,the vacuum characteristic and the ultraviolet characteristic of the diffuse reflector plate are proposed respectively.Through the comparison of different measurement methods to select the appropriate measurement method,set up with the corresponding measurement device,and get the measurement results.3)Analysis of Characteristic Measured results of Diffuse ReflectorBased on the in-depth analysis of the measurement results,it is concluded that the F4 target plate has a high reflectivity close to 0.99,a better spectral flatness,a bidirectional reflection distribution function of the approximate cosine distribution,a higher surface uniformity,The effect of UV vacuum.And the irradiation threshold of F4 target plate meet the requirements.4)the summary of the research and the prospect of the next stepThrough the analysis of the experimental results,the F4 target panel is the most suitable for the NBI system in the new generation ICF device.The results obtained in this study provide data support for the selection of the light collection scheme and the diffuse reflector material in the future NBI system.At the end of the paper,it shows the shortcomings of the research and puts forward some suggestions for the next research work.