The Icf Mcp Election Through Soft X-ray Picosecond Framing Camera Dynamic Spatial And Temporal Characteristics And The New Multi-time-resolved Diagnostic Techniques

The soft X-ray framing camera with the gated micro-channel plate(MCP-XFC)is the key ultra-fast diagnostic tool which can be used to capture 2D pictures of ultra-fast phenomena with high temporal/spatial resolution and is an ultra-fast precision measuring instrument which integrates ultra-fast photo-electronics and electronics,optics,vacuum technology and computing technology.The MCP-XFC is an important technologic support for the basic research of high-energy density physics,inertial confinement fusion(ICF), material science,photo-physics,photo-chemistry,ultra-fast spectroscopy,and laser plasma research,etc.The data taken by MCP-XFC are the important basis to analyze some ultra-fast processes.Based on the MCP-XFC technology development in China and abroad,a theoretical and experimental research of the dynamic temporal characteristics of the MCP-XPFC is using picosecond electronic pulse has been carried out and a new soft X-ray framing technology with multi-scale temporal resolution has been put forward to promote the ICF diagnostic technology applications and developmentIn this thesis,based on the theoretical model of electronic transit time and gain of DC MCP image,a fundamental theoretical model of MCP framing tube gated by the picosecond high voltage pulse is set-up first and then the characteristics of the dynamic temporal and spatial resolution of the MCP-XPFC gated by picosecond electrical pulse is discussedIn studying temporal resolution characteristics,the Uniform Design method is introduced into the design of MCP-XPFC,and the fast prediction model based on the parameters of gating pulses and dynamic temporal resolution is established.Whichin a certain range of parameters,the prediction model can replace the camera's temporal resolution theoretical model and give a quick guide of the experiment.In studying spatial resolution characteristics,the relation of the dynamic spatial resolution and the phosphor screen voltage,the proximity distance,amplitude and width of picosecond gating pulse have been studied.Taking frequently used parameters,the dynamic spatial resolution of MCP-XFC is calculated,some measures to improve the dynamic spatial resolution of the camera are discussed,and the method to optimize the structure parameters of the camera has been proposed.To diagnose the processes of nuclear fusion,which have different reaction speed rate, such as ICF,Z-Pinch and magnetic confinement fusion,it is necessary to develop a new type of X-ray framing camera,which has an expanded range of temporal resolution.For this purpose,we designed and developed a new prototype camera,which is based on two pieces of gated MCPs that are contacted to each other as a Chevron structure and the micro-strip lines on the input surface of the Chevron MCP are normal to those on the output surface of the MCP.Both micro-strip lines on the input surface and the output surface of the framing tube are provided with some high voltage pulses respectively and their gating order can be controlled by delay time so that its widely tunable exposure time (ps～us) and 16 frames of high gain(～10⁸) 2D pictures can be obtained.In comparison to single MCP-XPFC,the new type of camera can reduce the background noise brought by the X-ray straight through,increases the image gain,and therefore,it can improves image quality.The theoretical and experimental studies demonstrated that by controlling the pulsed width and interval of two cascade gating pulse,the multi-scale temporal resolution images can be acquired.On the basis of theoretical and experimental study of the new prototype camera,the method using one positive and one negative ps gating pulses as a cascades gating to decrease the temporal resolution is discussed.The results of the theoretical and experimental study show,when cascades gating pulse width and electron average transit time in MCP channel is less than or rather,by changing and controlling the pulse interval between two cascade gating pulses,the temporal resolution of camera can be improved to 45ps.By using narrow gating pulse to gate a framing camera which consists of a single thin MCP with small L/D ratio,it is possible to get a time resolution of 40ps.By adding an ordinary MCP behind the single thin MCP,the disadvantages induced by the thin MCP, such as low gain,low SNR and the light passing through the MCP channel directly can be overcome. In brief,the paper has demonstrated theoretically and experimentally that the time resolution of the gated micro-tripe MCP framing camera can be improved from 60ps to 45ps by using one gating pulse which has a width equal to the electron average transit time in the thin MCP channel.During carrying out this research,a platform named "ultra-fast diagnosis and high power laser physics experiment" has been set-up by ourselves.This platform contains a multi-wavelength 3TW femtosecond Ti:sapphire laser source,a high vacuum multi-function vacuum target chamber,a high-speed high resolution CCD camera and some ultra-fast diagnostic equipments such as sensitive to infrared,visible light,ultraviolet, and X-ray streak cameras and framing cameras,etc.The platform,therefore,not only can provide a high density,IR-XUV,fs light source for testing of static and dynamic characteristics of high temporal resolution diagnosis instruments but also can be used to carry out researches on interaction between ultra-short laser and material.