时间展宽分幅变像管时空性能研究

发布时间：2018-04-30 23:34

本文选题：惯性约束聚变 + 超快诊断技术　；参考：《深圳大学》2017年博士论文

【摘要】：分幅相机利用变像管实现图像的光电转换、脉冲选通和图像增强,是研究超快现象的主要工具。在惯性约束聚变(Inertial Confinement Fusion,ICF)的最后阶段,聚变燃烧持续时间为~l00 ps,此时靶核被压缩至几十微米,对该阶段等离子体时空演化的测量要求X射线分幅相机具有微米量级的二维空间分辨能力和优于30 ps的时间分辨能力。因此,为满足高时空分辨的ICF诊断实验要求,本论文对时间展宽分幅变像管的时空分辨性能展开研究,期望探寻一条提升X射线分幅变像管时间分辨性能的有效途径,为我国ICF的研究提供一种具有良好时空分辨性能的超快诊断设备。在总结国内外分幅摄影技术发展的基础上,本论文对时间展宽分幅变像管的时空分辨性能展开了理论研究和实验测试,完成的主要工作包括以下几个部分:1、采用短磁聚焦成像系统设计了时间展宽分幅变像管,通过对变像管系统整体结构的描述,分析了电子束产生与传输系统,磁透镜成像系统和MCP选通分幅变像管系统的工作原理,为建立变像管模型提供了理论依据;2、在时间分辨性能理论研究方面,模拟了像管时间分辨率,当漂移距离为500 mm、阴极电压为-2 kV和展宽脉冲斜率为10 V/ps时,电子束时间展宽技术可将分幅变像管时间分辨率提升至~2.24 ps,并研究和分析了漂移距离、阴极电压和展宽脉冲斜率等参数对时间分辨性能的影响。研究结果表明,漂移距离的增加能提高电子束展宽倍率,使像管时间分辨性能获得提升,但当电子束的展宽倍率提高到一定程度时,像管时间分辨性能的提升变得相对缓慢;阴极电压的提高,使电子束时间展宽倍率变小,引起像管时间分辨性能变差;而提高展宽脉冲斜率,能提高电子束展宽倍率,使像管时间分辨性能获得提升。综合以上结论,在选择适当漂移距离的同时,降低阴极电压和提高展宽脉冲斜率能快速提升像管时间分辨性能。3、在空间分辨性能理论研究方面,模拟了单/双磁透镜时间展宽分幅变像管的空间分辨率和成像面。当电子图像的成像比例为1:1时,单磁透镜像管轴上空间分辨率为61μm,离轴10 mm处的空间分辨率优于200μm;双磁透镜像管轴上空间分辨率为45μm,离轴20 mm处的空间分辨率优于200μm。采用球差和场曲理论分析了两种像管空间分辨性能存在差异的原因,对提高阴极电压和减小阴栅间距能提升像管空间分辨性能的原因展开了分析。模拟与分析结果表明,短磁聚焦时间展宽分幅变像管的成像面为一抛物面,其空间分辨性能随离轴距离增加而变差,而双磁透镜能减小球差和场曲的影响,使像管离轴空间分辨性能优于单磁透镜像管。4、采用2号分辨率板和刻有分辨率板的大面积阴极,测试了短磁聚焦时间展宽分幅变像管的静态性能。当电子图像的成像比例为1:1时,测得单/双磁透镜像管的轴上空间分辨率分别为79.5μm和75μm;当电子图像的成像比例为2:1时,单磁透镜像管阴极离轴~10.5 mm处的空间分辨率为200μm,双磁透镜像管阴极离轴~22.5 mm和~30 mm处的空间分辨率分别为200μm和500μm。测试了场曲和阴栅间距对像管空间分辨性能的影响。测试结果显示:短磁聚焦时间展宽分幅变像管的轴上空间分辨率优于100μm,采用双磁透镜成像的像管具有更好的离轴空间分辨性能,测试结果和分析结论与理论模拟相一致。5、采用延时光纤束测试了短磁聚焦时间展宽分幅变像管的动态性能,通过一幅动态图像获得了像管的时间分辨率和动态空间分辨率。当电子束时间宽度未被展宽时,像管时间分辨率为~105 ps,而采用电子束时间展宽技术后,时间分辨率提升至~11 ps。在电子图像的成像比例为1:1时,单/双磁透镜像管的近轴动态空间分辨率均优于100μm,调制度分别为11%和16%。。本论文工作的主要创新点如下:1、提出将短磁聚焦技术、电子束时间展宽技术和MCP行波选通分幅技术相结合来研制新型的时间展宽X射线分幅变像管,使得分幅变像管能够获得更好的时间分辨性能。2、采用延时光纤束法对变像管动态性能进行测量。美国研究者采用Mach Zehnder干涉仪,通过六幅动态图像获得相机时间分辨率,但由于实验中激光脉冲和电脉冲的触发晃动会引起这种方法出现测量误差,所以,本文采用延时光纤束法,通过一次测量(即一幅动态图像)就能获得分幅变像管的时间分辨率和动态空间分辨率,以此避免了触发晃动带来的测量误差。
[Abstract]:In the last phase of Inertial Confinement Fusion (ICF), the duration of fusion combustion is ~l00 PS, at the last stage of the inertial confinement fusion (ICF), the target core is compressed to dozens of microns at this time, and the spatio-temporal evolution of the plasma at this stage is presented. The measurement of the X ray division camera requires the two dimensional spatial resolution of the micron scale and the time resolution superior to 30 PS. Therefore, in order to meet the requirements of the ICF diagnosis experiment with high temporal and spatial resolution, this paper studies the space-time resolution performance of the time broadened image tube with time broadening, and hopes to explore a time division of the X ray image tube. The effective way of identifying performance provides a super fast diagnostic equipment with good space-time resolution performance for the research of ICF in China. On the basis of summarizing the development of the technology of amplitude division photography at home and abroad, this paper has carried out a theoretical study and experimental test on the space-time resolution performance of the time widening image tube. The main tasks completed include the following 1, 1, using the short magnetic focusing imaging system to design the time widening image tube. Through the description of the overall structure of the image tube system, the working principle of the electron beam generation and transmission system, the magnetic lens imaging system and the MCP selective amplitude variant image tube system are analyzed, which provide the theoretical basis for the building of the image tube model; 2, in the time resolution. In the field of performance theory, the time resolution of the image tube is simulated. When the drift distance is 500 mm, the cathode voltage is -2 kV and the width of the broadening pulse is 10 V/ps, the time resolution of the electron beam can be raised to ~2.24 PS, and the parameters of the drift distance, the cathode voltage and the width of the broadening pulse are studied and analyzed. The results show that the increase of the drift distance can increase the broadening ratio of the electron beam and improve the time resolution of the tube, but when the broadening ratio of the electron beam is increased to a certain extent, the enhancement of the time resolution of the image tube becomes relatively slow; the increase of the cathode voltage makes the time of the electron beam widen the multiplex. As a result, the time resolution of the image tube is worse, and the increase of the width of the broadening pulse can increase the broadening rate of the electron beam and improve the time resolution of the image tube. The conclusion is that the time resolution performance of the image tube can be rapidly improved by reducing the voltage of the cathode and increasing the width of the broadening pulse while the appropriate drift distance is selected, and the spatial resolution of.3 can be resolved in space. In the field of performance theory, the spatial resolution and imaging surface of a single / double magnetic lens have been simulated. When the imaging ratio of the electronic image is 1:1, the spatial resolution of the mono lens image tube axis is 61 u m, the spatial resolution of the 10 mm off axis is better than 200 u m, the spatial resolution of the dual magnetic lens image tube is 45 mu m, and the off-axis 20 m The spatial resolution of the M is superior to 200 m.. The difference between the spatial resolution of the two kinds of image tubes is analyzed by the theory of spherical aberration and field curvature. The analysis of the reasons for increasing the cathode voltage and reducing the gap between the negative grid can improve the spatial resolution of the image tube. The simulation and analysis results show that the short magnetic focusing time broadened the image image of the image tube A parabolic surface is a paraboloid, and its spatial resolution becomes worse with the increase of the distance from the off axis. The dual magnetic lens can reduce the effect of the spherical aberration and the field curve. The space resolution of the image tube is better than that of the mono magnetically permeable mirror.4. The 2 resolution plate and the large area cathode with the resolution plate are used to test the static state of the short magnetic focusing time broadening image tube. Performance. When the imaging ratio of the electronic image is 1:1, the spatial resolution on the axis of the single / double magnetic mirror tube is 79.5 and 75 m respectively. When the imaging proportion of the electronic image is 2:1, the spatial resolution of the ~10.5 mm of the mono lens image tube cathode is 200 u m, the spatial resolution of ~22.5 mm and ~30 mm at the cathode off axis of the dual magnetic lens tube. The effects of the field curvature and the spacing of the screen on the spatial resolution of the image tube are measured at 200 m and 500 micron M. respectively. The test results show that the spatial resolution on the axis of the image tube is better than 100 u m, and the image tube with double magnetic lens imaging has a better off axis spatial resolution, the test results and the analysis conclusion and theory are obtained. The simulation phase is consistent with.5. The time resolution and dynamic spatial resolution of the image tube are obtained through a dynamic image. When the time width of the electron beam is not broadened, the time resolution of the image tube is ~105 PS, and the electron beam time broadening technique is used. When the time resolution is raised to ~11 PS. in the imaging ratio of electronic images to 1:1, the dynamic spatial resolution of the single / double magnetically permeable mirrors is better than 100 mu m. The main innovation points of this thesis are as follows: 1, the short magnetic focusing technology, the electron beam time broadening and the MCP traveling wave separation amplitude technique are proposed. Combining to develop a new time broadening X ray widening image tube, a better time resolution performance.2 can be obtained by the score image tube, and the time-delay fiber beam method is used to measure the dynamic performance of the image tube. The American researchers use the Mach Zehnder interferometer to obtain the time resolution of the camera by six dynamic images, but the experiment is excited by the experimental excitation. The trigger sloshing of light pulse and electric pulse will cause the measurement error of this method. Therefore, this paper uses a time-delay fiber beam method to obtain the time resolution and dynamic spatial resolution of the amplitude variant image tube by one time measurement (a dynamic image), so as to avoid the measurement error caused by the contact sloshing.

【学位授予单位】：深圳大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN143

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