In this paper, the finite element model of the fiber optic plates is established by using the finite element software. The simulation process is basically in line with the actual production process of the fiber optic plates. According to the simulation results, the deformation degree and speed of each part of the fiber optic plates in the process of melting pressure, as well as the changes of stress and strain of each part in the process of forming are analyzed. The results show that the deformation speed and degree of different parts are different in the process of melting pressure of fiber optic plates, especially the upper and lower end faces and side edges of fiber optic plates; and the stress and strain of each part are constantly changing, and the stress and strain values of the upper and lower end faces and side edges of fiber optic plates are larger than others.
The high gain of pumping end in end-pumped all solid state lasers can easily cause self-excited oscillation, which limits the output energy of Q-switched laser. In order to obtain a 1064 nm Q-switched laser with high energy, high conversion efficiency and compact structure, the following three aspects are mainly studied to suppress the self-excited oscillation caused by the end pump: (1) the doping concentration of active particles is optimized to reduce the end gain of laser medium, (2) the wavelength of pump light is changed by adjusting temperature of laser diode to deviate from absorption peak of Nd:YAG, (3) Nd:YAG rod is processed by tapered side, which improves the difficulty of self-excited oscillation. By using the above techniques, a 1064 nm Q-switched laser with output energy of 100 mJ is obtained at a pump current of 20 Hz and 170 A, and the corresponding dynamic to static Q-switching ratio is 77%. The three technical means proposed in this study complement each other and work together, providing a practical and effective technical way for obtaining high-energy end pumped Q-switched laser.
The microchannel-plate-based x-ray optics is a spherical crown containing millions of square microchannels, reflecting the small incident angle light at a certain angle through the inner wall of the channels. Structure defects may exist in the square microchannel array. In this paper, the effects of structure defects on the imaging performance were studied through simulation and MPO preparation experiment. The structure defects involved in the paper include two types, chamfered channels and tilting channels. The experimental results are consistent with the simulation images, proving that the simulations are correct. The results show that the imaging of MPO with standard square channels array is a symmetrical cross. The presence of chamfers in corner of the channels results in a weak secondary small cross in the 45° direction of the obvious cross. For the case that the channels are tilted slightly, the center of the cross deviates from the imaging center, and the cross becomes an asymmetric cross. This study provides a theoretical guidance for precise control of array structures in the preparation of MPO.
Micro-nano project by studying the micro channel plate surface micro convex particle sizes can produce a phenomenon of point discharge which causes the field emission, and particles on the surface on the micro channel plate mechanism, then through metallographic microscope classification and testing for different particle morphology, finally three kinds of particle preparation is be determined. Through the study, by water to remove the ultrasonic repeatedly can get rid of polishing powder residue. And acid etching process of silica particles by adding alkali ultrasonic frequency and the use of high frequency ultrasound alternately can be completely removed. Then through evaporation before increasing ion bombardment can effectively control the micro convex particles which is produced after evaporation electrod. Through the study, by water to remove the ultrasonic repeatedly can get rid of polishing powder residue. And acid etching process of silica particles by adding alkali ultrasonic frequency and the use of high frequency ultrasound alternately can be completely removed. Then through evaporation before increasing ion bombardment can effectively control the micro convex particles which is produced after evaporation electrod.
Cracks in microchannel plate (MCP) seriously reduce the mechanical and electrical properties of MCP. The generation mechanism of cracks and the structure of sub-surface damage layer were revealed by studying the changes of surface morphology of MCP in optical process and chemical treatment process. The source of cracks appeared in the etching and reduction process is the sub-surface damage layer in the optical process. The damage layer includes cracks and non-uniform strain layer. After slicing, the depth of damage layer visible to optical microscope is within 25μm. During the polishing process, the damage layer is deeper, and there is a non-uniform strain layer with the depth of about 20μm. To avoid the occurrence of cracks, the thickness setting in the slicing process should take into account the slice damage layer, the polishing crack growth layer, and the strain layer.
The optical imaging system is the the core device in the extrem ultraviolet (EUV) astronomical telescope. Because of its light weight, large field of view, high resolution, the lobster-eye optical imaging system is considered to be the best imaging system for EUV. The curved square hole microchannel plate is an imitation lobster-eye type optical imaging system. The channels of the traditional curved square hole microchannel plate are generally arranged in a square shape, and the image is a cross image, which only the cross area is effectively detected, so the detection efficiency is low. In this paper, all the square hole channels are pointed to the center by radial arrangement, thereby the detection efficiency is improved. However, this arrangement cannot achieve close alignment, and there are a large number of voids in the structure, which reduces the density of the focusing unit. In this paper, the simulation of the radial arrangement of the square hole microchannel structure is carried out by Tracepro simulation software. Through the high-precision wire drawing method, radial arrangement technology, and distortion-free control, the drawing precision of the square wire is improved, the square wire structure defects are eliminated, and the square hole microchannel plate with uniform structural height is prepared.
As the core component of image intensifier, the electronic multiplication performance of microchannel plate determines the ability of the device to detect weak signals. The theoretical model of electron gain is the theoretical basis for the secondary electron multiplication of microchannel plates. It has important theoretical significance for the research of high performance microchannel plates and image intensifiers. In this paper, the theoretical model and simulation of electron gain in microchannel plates are reviewed. The electronic gain model and the modified theoretical model of the "energy proportional hypothesis" are emphatically introduced. On the basis of the model, some improvements are made and good simulation results are obtained. The behaviors of electron transport, collision and multiplication in microchannels based on the theoretical model of electronic gain and Monte Carlo stochastic calculation method are summarized. The differences among the three models are analyzed, and the problems existing in the theoretical model and simulation of electronic gain at present are analyzed. Finally, aiming at the shortcomings of theoretical model and simulation, the direction of improvement and optimization is put forward.
Crack in microchannel plate (MCP) seriously reduces the mechanical and electrical properties of MCP. The mechanism of crack propagation in the chemical treatment process was revealed by studying the changes of crack morphology in acid-alkali etching and hydrogen reduction. The results show that during the acid-alkali etching process, the cracks on the channel material is dissolved by the dilute HNO3 and the cracks on the channel wall expands gradually under the etching of the NaOH solution. During the reduction process, cracks do not change significantly at the stage of heating. While at the stage of reaction with H2，the cracks are more easily expanded. The length of cracks does not change significantly after reduction. However, the surface near the cracks warps and the depth of cracks increases.
Resistive Plate Chambers are planar, gaseous detectors made with electrodes and resistive plates, which is divided into single-gap (RPC) and multi-gap (MRPC). Such detectors have a simple structure, good time resolution, high efficiency, small dead zone, flexible signal readout mode and a relatively low cost, etc. Therefore, it has extensive and important applications in high energy physics, nuclear physics and other fields. The resistive glass plate has good stability and is less affected by the environments, which ensures the uniformity of the electric field inside the detector and makes the detector have lower dark current and noise. In this paper, the influence mechanism of resistive glass on detector performance was introduced firstly. Then the application and research status at home and abroad were summarized. On this basis, the existing problems in the research of resistive glass were expounded. Finally, according to the application requirements of RPC under the condition of high particle fluxes, the future development trend was analyzed and proposed. The author believes that it is the future development trend and direction in the field of resistive glass to carry out research on high-performance resistive glass materials and develop pure electronic conduction glass materials with volume resistivity of 109Ω•cm ~1010Ω•cm through composition design and control. At the same time, in order to meet the manufacturing requirements of large area array detectors, the strength, chemical stability and the possibility of batch manufacturing of the glass should also be fully considered in the development process of resistive glass.