Study On The Refractive Index Interference Detection Technology Of ICF Target

The target ignition experiment is of much importance in inertial confinement fusion(ICF)research,for which fusion happened only if the ignition succeed.It must be avoided that ignition failed for the poor quality of the target pill because every time of ignition is a great consumption of the resource and effective detection of the ICF target pills'physical characteristics must be provided in advance.It is an important step verifying whether ICF target pills meet the ignition conditions to detect their refractive index.Based on the previous work we had done in the group and a Mach-Zehnder style refractive index interference detection system of ICF target,the key data processing techniques of the system were proposed.Details were discussed from four aspects in this thesis which include basic principle of the detection,digital image processing of ICF target fringes,the wave-front phase processing and the design of operation software for the system.Precise detection of refractive index of the target pills was achieved with high efficiency.The main work I did are as follows:The data processing techniques of refractive index interference detection system of ICF target were proposed and improved.Precise circle center of the ICF target pill's fringes was calculated effectively basing on fringe orientation information,following which the fringes were exactly extracted from the interferograms transformed from Cartesian to polar coordinates.The wave-front phase data obtained from the refractive index interference detection system of ICF target was re-processed by Zernike polynomial fitting,by which the system error distribution was properly analyzed.Wave-front phase processing technique was studied.The path-dependency was explained which occurred when one-dimensional phase unwrapping was applied to the two-dimensional situation directly.The distribution characteristics of noise in the wave-front phase were analyzed and the effects of direct or indirect methods applied on the phase were compared.A software for the refractive index interference detection system of ICF target was designed and achieved.Proper function specification was proposed according to the operation flow of the detection system.A software development model that separate the user interface design from the functional implementation was applied when the software was developed,not only improving the development speed but also retaining the execution efficiency and result was shown to prove the work helpful in this thesis,basing the real interfering data and the software.