Research Of 3mm Quasi Optical Path In MIR Diagnostic System At Fusion Plasma

Energy supply is the key to the development of human society.The massive use of fossil energy pushes mankind into the industrial age.With the development of the human society,the increasing needs of energy leads to the depletion of fossil resource,and the pollution threatens the environment.As one of the most important ways to solve the energy problem,the difficulty of controlled nuclear fusion is reaction conditions.Now,the control of nuclear fusion is realized mainly by two methods: magnetic confinement and inertial confinement.Tokamak is one of the most ideal magnetic confinement devices.In recent years,many countries have made a lot of progress in the study of nuclear fusion in tokamak.A variety of diagnostic instruments based on microwave reflectometry are also used for plasma diagnostics in tokamak.The study of the anomalous transport in magnetized plasmas is related to the realization of magnetic confined fusion.The measurement of the electron density turbulence is the key to understand the anomalous transport in plasmas.Microwave Imaging Reflectometry(MIR)is a new method for the measurement of electron density turbulence in plasmas.Microwave Imaging Reflectometry combines Microwave Reflectometry and quasi optical imaging technology,which can realize the imaging of electron density turbulence information of plasmas,is an important diagnostic method for magnetized plasmas.The difference between the Microwave Imaging Reflectometry system and the conventional microwave reflectometry diagnostic system is the use of the quasi optical system.In the design of the quasi optical system,the matching of the wavefront curvature radius and the radius of the Gauss beam spot is the key of the design.This paper firstly introduces the theory of optical imaging,the classification of aberrations produced by optical systems.Then introduces the propagation characteristics of quasi Gauss beam in millimeter wave quasi optical technology,describes the basic theory of microwave Microwave Imaging Reflectometry,as a theoretical basis for the design of the quasi optical system.On this basis,a quasi optical system of the 3mm Microwave Imaging Reflectometry system using lens is designed and simulated by CODE-V optical simulation software.The system achieves a spatial resolution of 2cm to 5cm.In addition,in consideration of the reflection loss of the lens,another set of quasi optical system partially using mirrors is designed,and the aberration is smaller than that of the previous system.And in this thesis,aiming at measuring of the Gauss beam quality in Microwave Imaging Reflectometry system,a set of quasi optical beam automatic testing system is developed,an automatic test software is programmed based on LabVIEW,which realize the automatic measurement of Gauss beam power distribution.The effectiveness of the automatic test system is tested on the 8mm microwave reflection imaging experimental platform.