Wide-angle Shock Wave Velocity Diagnostic Method And Related VISAR Technology In Laser Fusion

In inertial confinement fusion,wide-angle shockwave velocity diagnostic method can be used for research of laser plasma interaction,compression asymmetry,and hydrodynamic instability,observing compression state of implosion drive,and provide reference data for optimization of driven laser and ignition target design;the experimental data can also be used to provide boundary conditions for solving equation of state to obtain thermodynamic state parameters such as temperature,density,and pressure.Velocity interferometer system for any reflector(VISAR)is one of the main testing methods in shock wave measurement.However,the restriction of current VISAR is:continuous measurement of one or two lines on a plane,measurement at specific moments on a plane,or measurement of several azimuth points in space.There is a lack of method for continuous measurement of shock wave velocity in full space.The main work in this thesis is:The concept of wide-angle shock wave velocity diagnosis is proposed and optical properties of system are studied.The shape parameters of the stereoscopic mirror surface required for wide-angle diagnosis are calculated and determined.The study of wide-angle diagnostic imaging properties is carried out.It is found that the imaging bending can affect the appearance of interference fringes.The effect of imaging bending on the formation of dynamic interference fringes is simulated by Zemax and a shaped opticalfiberplate is proposed for image correction.The influence of assembly error is also studied.To obtain a good imaging result,the positional deviation of the ellipsoidal mirror should not exceed 30?m,the inclination should not exceed 4°,the manufacturing error requires less than 0.1 ?m in long axis direction and 4?m in short axis direction,and reflectance needs to be higher than70%.More possible factors of affecting dynamic fringes,other methods of imaging correction,correspondence between object andimage are discussed,along with the potential developmentof wide-angle VISAR.The optical properties of wide-angle VISAR is a basis forimprovingthe wide-angle diagnosticcapability,and is of great significance for the quantitative observation for driving symmetry of capsule ininertial confinement fusion.Experiments have been carried out to verify the technical feasibility of wide-angle shock wave velocity diagnosis.According to the driving environment of the Shenguang ? prototype,the configuration and materials of the wide-angle diagnostic experimental target were selected.The target ablation under laser driving was simulated,and the experimental parameters of the platform capable of detecting dynamic interference fringes were developed.The direct-drive wide-angle shock wave diagnostic experiment obtained dynamic interference fringes which reflected the driving compression symmetry.The development direction of wide-angle shock wave diagnostic experiments in imaging recording,target design,equipment loading and supplementation are discussed.A high temporal resolution numerical algorithm for shock wave velocity diagnosis is proposed.By analyzing variations in the optical path and phasor of the light field,we determine a high temporal resolution shock wave velocity equation for a velocity interferometer system for any reflector(VISAR).The equation can be transformed into matrix form for numerical solution.To solve the noise problem,a"filtering velocity spectrum"method is proposed.Analysis of a VISAR data example shows that the resolution precision of shock wave velocity obtained from the numerical algorithm is the same as the temporal resolution of a streak camera.Moreover,it can observe the shock wave in greater detail.This algorithm can be used to observe detailed images and determine the mechanism and evolution of extreme shock waves,as well as provide data for research into hydrodynamic behavior in inertial confinement fusion.The line imaging VISAR is modified to achieve different measurement functions.The improvement is mainly reflected in the three aspects:image light path,etalon and recording system.A multi-function laser fusion diagnostic interferometer,a fiber-optic image beam velocity interferometer,a four-sensitivity laser fusion shock wave velocity measurement interferometer,a wide-range shock wave velocity diagnostic device,a laser fusion target particle state information stereo measurement system and a laser fusion target state information multi-axis measurement system are proposed.These improvements are expected to be used in the wide-angle shockwave velocity diagnosis in the future.