Study Of3D Imaging Technology For The ICF Application

In Inertia Confinement Fusion (ICF) experiment, the symmetry and uniformity ofpellet compression is the precondition of efficient pellet implosion. Therefore, thepellet compression process must be observed in order to obtain pellet compressionsymmetry, plasma hydrodynamics instability and laser irradiation uniformity andother important physical information. Traditional diagnostic equipment such asframing cameras, pinhole cameras capture two-dimensional projection images of thethree-dimensional spherical implosion pellet in a direction. It can only record thecontours of the pellet without depth information. Accordingly, they cannot reflect thepellet compression density changes during the process of experiment, and thereforeare difficult to achieve a higher diagnostic accuracy.In order to solve such problem, the classical image reconstruction techniques inmedical CT (Computed Tomography) are applied to the deal with the3D imagereconstruction of ICF experiment in this paper. The basic principles of CT imagereconstruction and several common reconstruction methods are firstly introduced, andthen the primary factors that affect the reconstruction precision are studied. A newiterative algorithm (Simulated Annealing Multi-criterion Reconstruction Technique,SAMRT) is proposed and demonstrated by numerical simulation, which is based onSIRT (Simultaneous Iterative Reconstruction Technique). Design the3Dreconstruction numerical model of pellet, and then generate the projection data from it,according to the transmission character of X-ray and imaging principle of framingcamera. Reconstruct the3D image of the pellet model using the traditional algorithmand the new algorithm proposed in this paper.In this paper, the mainly research work includes:(1) Aimed at the limitation of traditional diagnostic equipment, the CT imagereconstruction algorithms are introduced to ICF diagnostic filed. simulating the3Dimage reconstruction course of ICF by using the two-dimensional projection imagecaptured by framing cameras. Evaluate the feasibility simulation of several differentCT image reconstruction algorithms in ICF application. Establish the quantitativerelationship of reconstruction performance indexes and related parameters andpropose the effective selection method for the parameters in iterative algorithms. Theprimary factors affecting the reconstruction precision of CT image reconstruction are studied and analyzed, which provides the theoretical support for the improvement ofthe reconstruction algorithms in the future.(2) By introduced the simulated annealing algorithm and multi-objectiveoptimization theory, a new iterative algorithm (SAMRT) based on traditional SIRTtechnique is proposed and compared with the traditional algorithms by numericalsimulation.(3) Design the3D reconstruction numerical model of the pellet and generate theprojection figures according to the transmission character of X-ray and the imagingprinciple of framing camera. Three-dimensional reconstruction simulation is done bythe traditional methods and SAMRT technique from the two-dimensional projectionfigures to compare the reconstruction accuracy of these methods.