Design and development of radio frequency output window for circular electron–positron collider klystron

This paper presents the first phase of design, analysis, and simulation for the klystron coaxial radio frequency(RF)output window. This study is motivated by 800 kW continuous wave(CW), 650 MHz klystrons for the future plan of circular electron–positron collider(CEPC) project. The RF window which is used in the klystron output section has a function to separate the klystron from the inner vacuum side to the outside, and high RF power propagates through the window with small power dissipation. Therefore, the window is a key component for the high power klystron. However, it is vulnerable to the high thermal stress and multipacting, so this paper presents the window design and analysis for these problems. The microwave design has been performed by using the computer simulation technology(CST) microwave studio and the return loss of the window has been established to be less than-90 d B. The multipacting simulation of the window has been carried out using MultiPac and CST particles studio. Through the multipacting analysis, it is shown that with thin coating of TiN, the multipacting effect has been suppressed effectively on the ceramic surface. The thermal analysis is carried out using ANSYS code and the temperature of alumina ceramic is lower than 310 K with water cooling.The design result successfully meets the requirement of the CEPC 650 MHz klystron. The manufacturing and high power test plan are also described in this paper.     

Optical humidity-sensitive mechanism based on refractive index variation

A novel composite model is put forward for humidity-sensitive material based on Maxwell-Garnett and effective medium theory. The analytical expression of the relation between effective refractive index and relative humidity is shown with different absorption factors and porosities. The larger the absorption factor is, the higher the refractive index is. The refractive index of humidity-sensitive SiO2 film decreases with the increase of ceramic material porosity. The sensitivity of optical humidity sensor can reach the magnitude of 10-3. In comparison with the experimental humidity-sensing curve by the method of p-polarized reflectance and the analysis of mechanism, theoretical simulation is in agreement with experimental results. Therefore, this composite model is proved to be reasonable which lays new theoretical foundation in further research on optical humidity sensor.     

PSPICE controlled-source models of analogous circuit for Langevin type piezoelectric transducer

The design and construction of wide-band and high efficiency acoustical projector has long been considered an art beyond the capabilities of many smaller groups. Langevin type piezoelectric transducers have been the most candidate of sonar array system applied in underwater communication. The transducers are fabricated, by bolting head mass and tail mass on both ends of stacked piezoelectric ceramic, to satisfy the multiple, conflicting design for high power transmitting capability. The aim of this research is to study the characteristics of Langevin type piezoelectric transducer that depend on different metal loading. First, the Mason equivalent circuit is used to model the segmented piezoelectric ceramic, then, the impedance network of tail and head masses is deduced by the Newton's theory. To obtain the optimal solution to a specific design formulation, PSPICE controlled-source programming techniques can be applied. A valid example of the application of PSPICE models for Langevin type transducer analysis is presented and the simulation results are in good agreement with the experimental measurements.     

Scattering loss and efficiency of the multi-pass mini-slab Nd:YAG ceramic lasers

Multi-pass mini-slab (MPMS) Nd:YAG ceramic lasers with a single-mode output of 38 W is examined corresponding to an optical conversion efficiency of 47%. Although several characteristics of various ceramic samples are almost similar, such as transmission, emission and absorption spectra, cross section, and thermal conductivity, their optical conversion efficiencies can vary from 5% to 40%. We present a simple technique to on-line measure the influence of scattering loss of ceramic on laser performance. This particular technique provides convenience and accuracy in pre-monitoring ceramic sample quality. Experimental results of the MPMS Nd:YAG ceramic laser agree with evaluations.     

End-Pumped Tm:YAG Ceramic Slab Lasers

Lasers from a Tm：YAG slab is end-pumped by continuous-wave output of the Tm：YAG ceramic ceramic am~e reported for the t~rst time to our best knowledge. The Tm：YAG ceramic a laser diode with central wavelength 792nm. At room temperature, the maximum power is 4.5 W, and the sloping efficiency is obtained to be 20.5%. The laser spectrum is centered at 2015nm.     

Wireless contactless pressure measurement of an LC passive pressure sensor with a novel antenna for high-temperature applications

In this paper, a novel antenna is proposed for high-temperature testing, which can make the high-temperature pressure characteristics of a wireless passive ceramic pressure sensor demonstrated at up to a temperature of 600°C. The design parameters of the antenna are similar to those of the sensor, which will increase the coupling strength between the sensor and testing antenna. The antenna is fabricated in thick film integrated technology, and the properties of the alumina ceramic and silver ensure the feasibility of the antenna in high-temperature environments. The sensor, coupled with the ceramic antenna, is investigated using a high-temperature pressure testing platform. The experimental measurement results show that the pressure signal in a harsh environment can be detected by the frequency diversity of the sensor.     

A high-power high-stability Q-switched green laser with intracavity frequency doubling using a diode-pumped composite ceramic Nd：YAG laser

We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd:YAG in a straight plano-concave cavity. The temperature distribution in composite ceramic Nd:YAG crystal is numerically analyzed and compared with that of conventional Nd:YAG crystal. By using a composite ceramic Nd:YAG rod and a type-II high gray track resistance KTP (HGTR-KTP) crystal, a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz, with a diode-to-green optical conversion of 14.68%, and a pulse width of 162 ns. To the best of our knowledge, both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd:YAG laser to date. The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.     

Critical Biot's number for Determination of the Sensitivity of Spherical Ceramics to Thermal Shock

A critical Blot number, which determines both the sensitivity of spherical ceramics to quenching and the durations of the temperature-wave propagation and the thermal stresses in the ceramics subjected to thermal shock, is theoretically obtained. The results prove that once the Blot number of a ceramic sphere is greater than the critical number, its thermal shock failure will be such a rapid process that the failure only occurs in the initial regime of heat conduction, whereas the thermal shock failure of the ceramic sphere is uncertain in the course of heat conduction. The presented results provide a guide to the selection of the ceramics applied in the thermostructural engineering with thermal shock.     

Influence of annealing temperature on the performance of Ge film and photon-counting imaging system

<正>Compared with the traditional image intensifier with phosphor screen readout,the photon-counting imaging detector with charge induction readout is more beneficial in several aspects(e.g.,good imaging properties and time resolution) to astronomy,reconnaissance,bioluminescence,and materials research.However, the annealing temperature during the tube-making process can affect the properties of the Ge film,and consequently impair the performance of the detector.Therefore,the influence of annealing temperature on Ge film and on the detector is studied in order to determine the crucial parameters.The Ge films are prepared on ceramic and quartz glass by the use of an electron gun.They are analyzed by scanning electron microscope(SEM),high-resistance meter,and X-ray diffraction(XRD).The results show that the optimum substrate and annealing temperature are ceramic plate and 250℃,respectively.     

Wear analysis of revolute joints with clearance in multibody systems

In this work, the prediction of wear for revolute joint with clearance in multibody systems is investigated using a computational methodology. The contact model in clearance joint is established using a new hybrid nonlinear contact force model and the friction effect is considered by using a modified Coulomb friction model. The dynamics model of multibody system with clearance is established using dynamic segmentation modeling method and the computational process for wear analysis of clearance joint in multibody systems is presented. The main computational process for wear analysis of clearance joint includes two steps, which are dynamics analysis and wear analysis. The dynamics simulation of multibody system with revolute clearance joint is carried out and the contact forces are drawn and used to calculate the wear amount of revolute clearance joint based on the Archard’s wear model. Finally, a four-bar multibody mechanical system with revolute clearance joint is used as numerical example application to perform the simulation and show the dynamics responses and wear characteristics of multibody systems with revolute clearance joint. The main results of this work indicate that the contact between the joint elements is wider and more frequent in some specific regions and the wear phenomenon is not regular around the joint surface, which causes the clearance size increase non-regularly after clearance joint wear. This work presents an effective method to predict wear of revolute joint with clearance in multibody systems.     

繁昌窑址附近多种瓷土成分分析

繁昌窑青白瓷胎体配方工艺一直停留在理论推理阶段，尚未有确凿的测试数据和模拟实验加以证实。为深入探究繁昌窑的胎料配方工艺，选取了繁昌窑址附近的多种瓷土样品进行了测试分析，并采用了古代制瓷工艺进行了模拟烧制。主要运用了波长色散X射线荧光光谱法(WDXRF)、红外光谱（FTIR）和X射线衍射（XRD）等光谱分析方法对瓷土成分进行测试；借助同步热分析（TG-DSC）对样品烧造温度进行了探索；通过模拟烧制陶瓷样品，对繁昌窑青白瓷的烧制工艺进行了研究，并对烧制的陶瓷样品进行显微结构分析。研究表明，繁昌窑附近的几种瓷土无论是单独制胎还是添加高岭土混合制胎，其烧成温度皆接近古代繁昌窑青白瓷的烧制温度。繁昌窑附近的瓷土是可以作为制作古代青白瓷的原料之一，但由于其中的铝含量较低，不能单独用来制作青白瓷胎体的原料，繁昌窑青白瓷在制作过程中应添加了其他富铝类原料。该研究对探索古代繁昌青白瓷的生产工艺及其蕴含的科学价值，提升繁昌窑在中国陶瓷工艺技术发展史上的地位等具有重要的学术意义，并可为现代陶瓷产业技术改进提供有益启示。     

基于OCT技术对古瓷釉气泡特征的初步研究

气泡是古代瓷釉中最常见的一种现象,气泡的大小与分布与胎体和釉层的配方及制作工艺密切相关。气泡表征对研究陶瓷的制作工艺、产地和时代特征等具有重要的意义。为了探讨利用光学相干层析成像技术（OCT）表征古代瓷釉中气泡及其分布特征的可行性,实验采用扫频OCT成像系统对五件不同类型的瓷釉样品进行了测试。根据实验所获得的透明釉层及胎釉结合部位的二维断面图像和三维层析图像,分别进行了瓷釉气泡二维断面和三维切片的特征研究,综合分析了釉层中的气泡特征及其可能产生的原因,认为釉层中的气泡主要是由于胎体中的气体在烧制过程中向釉层溢出所致;同时基于像素点计算了气泡的大小, 并与传统光学显微镜观测到的结果进行了比较;实验还针对不透明釉层中的气泡进行了大小计算、二维断面及三维切片的特征研究。实验结果表明,不同类型的古代瓷釉釉层中的气泡特征差异明显;基于像素点计算的气泡大小与传统光学显微镜测试的结果吻合, 近胎釉结合面的胎体切片能很好的反映瓷釉的气泡特征。本研究提出并验证了利用OCT技术表征瓷釉气泡特征的可行性与有效性,实现了釉层气泡特征的无损检测,特别是对不透明釉层气泡的分析,克服了以往利用传统显微镜技术对釉层气泡分布研究的局限,为古代陶瓷瓷釉的气泡特征分析提供了一种新型的、可靠的分析手段。     

An optically stimulated luminescence study of porcelain related to radiation dosimetry

This article describes the essential features regarding the photo-stimulated luminescence of porcelain: both the main ceramic and glazing materials are studied. In each case, radiation dose dependent signals are observed, superimposed on dose independent luminescence transitions that are both Stokes and anti-Stokes shifted in energy. Glazing is shown in some cases to be considerably more sensitive as a radiation dosemeter than the main porcelain ceramic. By comparison with the properties of artificial phosphors, the principal luminescent matrix is identified as being Al₂O₃, and the recombination centres in one glazing type are shown to be F-centres, Cr³⁺ and Dy³⁺.     

景德镇五代瓷器组成配方的EDXRF分析

景德镇早期制瓷工艺一直是学术界所关注的焦点问题之一。采用能量色散X射线荧光法分析了景德镇五代时期湘湖窑出土白瓷和青瓷样品的胎釉元素组成,并据此探讨其原料和配方。研究表明,五代时期景德镇湘湖窑白瓷胎体所用原料为瓷石,而青瓷瓷胎应是采用瓷石配以紫金土的二元配方;白瓷和青瓷瓷釉皆使用釉果加釉灰的配方,且青瓷瓷釉配方中釉灰的用量高于白瓷瓷釉。     

历代景德镇青花瓷光谱特征分析研究

景德镇青花瓷是我国最具代表性的陶瓷品种之一,具有很高的学术价值和社会经济价值。不同年代的青花瓷仅靠外观难以区分,如何快速准确区分不同年代的景德镇青花瓷是文物保护界面临的一个难题。高光谱技术是一种完全无损的分析方法,并已经在壁画、字画等文物的颜料分析中得到成功应用,目前还没有关于瓷器文物的高光谱研究成果出现。选取28个历代景德镇青花瓷碎片样本,使用地面光谱仪测量样本胎釉和青花料部位反射率光谱,分析其典型光谱特征,并对历代青花料光谱特征参量变化趋势进行了分析。研究表明,青花料部位在可见近红外波段光谱特征较为显著,历代青花料光谱特征参量有较明显的差异,并有一定的变化规律。高光谱技术对于景德镇青花瓷的断代研究有很大潜力。     

平顶山应国墓地出土原始瓷的制作工艺和产地

原始瓷一直是学术界所关心的重要问题,其产地和工艺关系到我国古代陶瓷发展模式以及商周文化面貌研究,具有十分重要的学术价值。采用XRF和XRD等科技手段,对最新出土的河南平顶山应国墓地遗址7枚原始瓷片进行了测试和产地推测。分析结果显示,应国墓地原始瓷瓷釉中磷含量明显偏高,暗示其使用了草木灰作为原料。与其他已发表的原始瓷数据相比,应国墓地出土原始瓷瓷釉的Ca/Al和P/Al值明显不同,暗示其配方工艺与南方产地产品有所差别。分析结果显示,应国墓地原始瓷产地不在南方。     

景德镇釉上彩绘瓷器釉上彩的Raman与EDXRF分析

釉上彩绘瓷器是我国古陶瓷中重要品类之一,具有极高的艺术价值和科学价值。采用拉曼光谱和能量色散X射线荧光分析等无损技术手段,对陶瓷釉彩的元素组成和物相组成综合分析,探讨了人们广为关注的景德镇元、 明和清代釉上彩绘瓷若干典型颜料种类的组成配方及其相应的呈色机制。研究发现景德镇古代红绿彩、 五彩、 粉彩等标本中的深红釉上彩料为赤铁矿着色,黄彩为铅锡黄着色,胭脂红彩则由含量不到0.1%的金所着色,绿料皆为二价铜离子着色。研究结果也进一步说明了Raman和EDXRF这两种无损、 微区分析技术的有效结合可以在深化陶瓷类文物的分析研究,尤其是针对图案交错复杂的多种彩绘颜料研究方面起到重要的作用。     

Proton induced X-ray emission (PIXE) analysis of sources of porcelain body of Ru Guan and Jun Guan porcelains

34 samples of Ru Guan porcelain body and 50 samples of Jun Guan porcelain body (both kinds being in different body colors) were selected with the purpose of finding out the source of raw materials and their classification relationship so as to search for ways of non-destructive discrimination. Proton induced X-ray emission (PIXE) has been applied to these samples to determine their chemical elements. The data of seven major chemical elements collected from these samples were further studied through fuzzy cluster analysis. Results indicate that the origin of raw materials of Jun Guan porcelain body samples is comparatively more concentrated in certain places, while that of Ru Guan porcelain body samples is scattered about. The places of origin of raw materials of the majority of Ru Guan and Jun Guan porcelain body samples have something in common, but some differences still exist. It might be an important way for non-destructive discrimination among Ru Guan and Jun Guan porcelains by combining PIXE with fuzzy cluster analysis.     

A comparative analysis of reticular crack on ceramic plate driven by thermal shock

Reticular crack is generally found on the surface of ceramic material that has been subjected to a thermal-shock condition. In the present study, a quantitative effect of thermal shock and quench temperature has been studied and investigated. Experimental tests were carried out to characterize the reticular crack that has been found in the Ge Kiln, which is a famous art of the ancient Chinese culture. After comparative analysis between thermal-shock cracks and the glaze crack patterns of the Ge Kiln porcelain, it is found that this study is expected to provide a powerful tool for recurrence of the long-lost firing and cooling process of the Ge Kiln porcelain.     

Influence of surface treatments on the shear bond strength of orthodontic brackets to porcelain

The purpose of this study was to investigate the effect of various surface treatments after different storage time and thermocycling on the shear bond strength of orthodontic brackets to the feldspathic porcelain surfaces. 128 disc-shaped porcelain specimens were randomly assigned to the following surface treatments: 9.6% HFA, 9.6% HFA combined with silane, 50 μ aluminum trioxide sandblasting followed by silane and application of silane after 37% phosphoric acid. Metal or ceramic brackets were bonded onto each treated porcelain facet with light cured resin. The samples were stored in 37 °C water 1 day or 7 days, thermocycled 500 times from 5 to 55 °C. The shear bond strengths were measured (1 mm/min), and statistically analyzed. The bond failure sites were classified according to ARI system. The surface of the glazed, sandblasted, hydrofluoric and phosphoric acid etched porcelain were examined with SEM. All groups achieved reasonable bond strengths to withstand the application of orthodontic forces. Water storage for 7 days caused lower shear bond strength than that of 1 day. But there is no statistically significant difference between the two groups. The mean shear bond strength provided by ceramic bracket with mechanical retention had no statistical difference with that of metal bracket. Therefore, the optimal treatment for orthodontic brackets bonding to feldspathic porcelain was to apply phosphoric acid combined with silane.