In view of the three working modes of the Roots vacuum pump unit in the start-up process, namely bypass mode, straight through mode and frequency conversion mode, the simplified calculation models are established respectively. The effective pumping speed calculation formula of the Roots vacuum pump unit are derived before the Roots pump enters the normal steady-state operation, as well as the calculation method of the pumping time of the pumped container. Through an example, the pressure time curves of three different start-up modes are obtained. It is proved that the pumping time of the container decreases in turn under the working modes of frequency conversion, bypass and straight through, and the frequency conversion start-up mode can save 46.58% of the pumping time compared with that of the straight through start-up mode.

The internal flow field of a subsonic evacuated tube train is complex,and it is important to study the effect of the tube cross-section shape on the aerodynamic properties. Based on computational fluid dynamics(CFD), considering the fluid viscosity and train suspension gap, a three-dimensional aerodynamic model of subsonic evacuated tube train is established. The aerodynamic drag, flow field characteristics and aerodynamic heating effect in 4 different cross-sectional tube are numerical simulated and compared. The results show that when the blockage ratio is constant, the aerodynamic drag of the train in an arched tube is the smallest, and then the circular tube, the largest in the rectangular tube. The pressure gradient in the vertical direction of the circular tube is the smallest, and the pressure on the upper surface of the tube is also the smallest. In the subsonic evacuated tube maglev system, the maximum temperature is shown on both sides of the train bump, and the minimum temperature is on the tube surface. Tube cross-section shape has few effects on the temperature distribution. When the area of the tube cross-section is chosen, the arched tube is prior recommended,and next choice is the circular tube.

Satellite needs to be able to unsealing and resealing at any time in the factory building without civil reconstruction,and the environment of storage conditions could be controlled.This article proposes a solution based on flexible storage methods,in view of storage requirements and related standards.According to the standard,a flexible storage system is designed,which mainly includes a variable support frame,a flexible sealing film and a monitoring system.We carry out mechanical and electrical design and finite element simulation calculation of structural strength of the supporting frame;research,analysis and test verification of the sealing performance,strength performance,and different gas permeability of the flexible sealing film;the software and hardware design of the storage environment monitoring system.Part of the specific design is carried out to realize the real-time monitoring and storage of temperature,humidity,pressure,cleanliness,nitrogen concentration and other parameters in the storage environment and the analysis of environmental data.Each part of the entire system adopts a modular design,the size of the space can be adjusted,and the configuration of monitoring sensors can be increased or decreased according to requirements.Different modules can be freely transplanted between systems to achieve generalization.Through the implementation of the storage solution based on the flexible storage system,the long-term flexible storage of the entire satellite under the controllable environment is realized for the first time.

In order to avoid the failure of metal materials due to hydrogen diffusion, oxide or nitride films are usually prepared on the surface of metal materials. The microstructure and crystal structure of the films have significant influence on the hydrogen resistance. In this paper, CrN hydrogen barrier films were prepared on stainless steel. The effects of high/low substrate bias modulation mode on the structure and hydrogen resistance of CrN films were studied systematically. CrN thin films with high temperature oxidation resistance were prepared by high power pulsed magnetron sputtering under four groups of substrate bias modes. The results show that under 20min×3 mode, the films are double-layer structure, and the others are single-layer films. When the substrate bias is 100V and 500V, the impact effect on the film is very different by ion. Under 10min×6 mode, the columnar crystal is broken before it grows because of frequent matrix bias change, so the film is the thinnest, but the grain is refined and the density of the film is the highest. Under 20min×3 mode, the hydrogen inhibition rate of the film was the highest, reaching 95.7%, the diffusion coefficient of hydrogen atom is the smallest, which is 3 orders of magnitude lower than that of 316L stainless steel. The oxidation resistance of CrN films is not much different under the four kinds of substrate bias modes, and the oxygen gain per unit area is about half of that of the 316L stainless steel. The oxidation resistance of CrN films prepared by this experiments is twice that of the 316L stainless steel, and they have excellent high temperature oxidation resistance.

The method of optimally designing experiments was introduced to study the properties of Al₂O₃:Ce luminescence thin films.Uniform design and quadratic general rotary unitized design were combined to build the equation between the luminescent intensity and the O^2-/Ce³⁺ doping concentration.Genetic algorithm was introduced into the calculation to obtain the best luminescent intensity.The optimal amorphous Al₂O₃:Ce thin films were deposited by the MF reactive magnetron sputtering technique.Under 320nm ultraviolet excitation,the blue emission spectrum was detected.The luminescence mechanism was studied.The photoluminescence emission from these films was associated with 5d¹ to 4f¹ transitions of Ce³⁺ ions.The intensity of these peaks was strongly dependent on the amount of cerium and oxygen incorporated in the films.There were some Ce³⁺ in the Al₂O₃:Ce thin films by XPS measurement.The presence of cerium as well as the stoichiometry of these films were determined by energy dispersive X-ray spectroscope measurements.The crystalline structure of the sample was analyzed by X-ray diffractometry.

ZnO thin films were deposited on glass substrate by magnetron sputtering ZnO ceramic targets. The phase structure, band gap, transmittance and microstructure of the films were investigated by X-ray diffraction,scanning electron microscope and multifunctional film tester. The results show that the ZnO films with（002）preferred orientation can be formed under different process parameters. The process parameters affect the transmittance of the films. The coverage of films is determined by the sputtering power.

As a band gap semiconductor material, Ga₂O₃ is considered to be a promising material owing to its ultra-wide band gap（4.9eV）, high breakdown field intensity and excellent thermal stability. β-Ga₂O₃/p-SiNWs heterojunctions were fabricated by RF magnetron sputtering of β-Ga₂O₃ layers onto the p-SiNWs substrates. The optical and electrical properties of heterojunctions were studied. The p-SiNWS showed excellent“light trapping” characteristics with the reflection coefficient to be 1/6 of the planar Si, which decreased gradually with the increase of the length of substrate nanowires. Photoluminescence spectroscopy（PL） tests showed that all the samples exhibited a typical green emission peak near 551nm at room temperature. β-Ga₂O₃/p-SiNWs heterojunctions showed obvious rectifying characteristics with rectifying coefficient of 1724 at V=1.40V. The ideal factor of heterojunctions increased gradually with the increase of length of substrate nanowires, and the optimal factor value is 1.98. The charge transfer mechanism of heterojunctions was investigated by logI-logV curve. The crystallinity of the β-Ga₂O₃ film was enhanced by annealing,which also improved the electrical properties of the heterojunctions.

Diamond coated tools show excellent hardness,wear resistance and thermal conductivity. In military, aerospace and other high-end fields, there is no substitute for diamond coated tools in the processing of graphite, high silicon aluminum alloy, carbon fiber reinforced plastic and other difficult cutting materials. However, there are two problems with diamond coated tools. One is the poor adhesion between the coating and the cutting tool, which leads to the coating falling off prematurely in use. The other one is that it is difficult to ensure the flatness and dimensional accuracy of the machined surface due to the large surface roughness of the coating. In this paper, the research results of diamond coating prepared by HFCVD in recent years are reviewed from the aspects of enhancing the adhesion and reducing the roughness of coating, and the influence of various factors on the performance of diamond coated tools is analyzed.

A new type of micro-focus electron source based on carbon nanotube field emission is developed. Laser ablation of the nickel substrate would melt the metal and spray the unoxidized metal inside to expose to the surface to form a hemispherical shell with a diameter of about 350μm,on which the carbon nanotube film is grown by the direct chemical vapor deposition technique. The micro-dimension electron source shows good field emission characteristic performances including low turn-on electric field（<1V/μm）, high emission current（up to 1A/cm²）, and stable high pressure emission stability. After addition of graphene materials and 750℃ annealing, the high-pressure emission stability is further improved. This work may provide an effective approach to prepare high-current micro-scale field emission cathodes.

The evaporation law of impregnated cathode for microwave vacuum electronic devices is summarized, and a pretreatment method of impregnated cathode is proposed. In the ultra-high vacuum, the cathode in the electron gun is heated. When the temperature rises to 1100~1200℃,and maintains for 1~200h(the temperature and time depend on different microwave tubes). This technology solves the contradiction between cathode emission and evaporation in the electron gun. More than a dozen impregnated cathode pretreatment equipments have been developed, which improves the insulation performance of the electron gun in microwave vacuum electronic devices and reduces the grid emission. At the same time, this technology can speed up the inspection of the reliability of the protons, thereby avoiding the problem of thermon disconnection caused by the defects of the heaters during the use of microwave devices, and improving the reliability of the heater in microwave vacuum electronic devices.

In this paper, in order to solve the problem of the automatic testing of vacuum and temperature parameters of the vacuum equipment, a high-precision platinum resistance thermometer is arranged inside the as-tested equipment, and a high-precision full range vacuum meter is arranged at the vacuum interface of the equipment to realize accurate data measurement. The computer automatically collects the measurement data of vacuum and temperature through Labview program, so as to realize the automation of joint detection of vacuum and temperature parameters of the vacuum equipment.

In order to verify the influence of different thermal connection modes in ultra-low temperature zone on the cooling of cryogenic radiation source, a vacuum thermal test system in ultra-low temperature zone was established, and the ultra-low temperature thermal conductivity characteristics of three types of thermal connectors were tested. The results show that the high purity copper and aluminum below 40K show excellent thermal conductivity performance. Under the premise of structural permits, the cooling time of the cold shield can be reduced by increasing the thermal cross-sectional area of the thermal connector, shortening the thermal path and reducing the heat capacity of the thermal connector. At the same time, the non-directional structure of cold shield can be optimized by using flexible thermal connectors. The results can be used to guide the structure optimization of cryogenic radiation source and the design of non-directional cryogenic radiation source, and provide experimental data for cryogenic radiation source test.

Combining the characteristics of composite coating equipment and coating process, this paper analyzes the process flow of composite coating equipment and the problems of energy consumption and pollution in the process in detail. On this basis, according to the vacuum system of equipment,work and water cooling system, control system and the synergy of each source of equipment, the intelligent composite coating equipment automatic control system is designed and realized using PLC and LabVIEW software collaboratively to ensure the stability and reliability of the coating equipment and process production, so as to improve the quality of coated products, save energy and reduce the pollution emissions to nature. The energy-saving comparison tests show that compared with ordinary equipment, the intelligent composite coating equipment saves about 25kW·h in one vacuuming process, the intelligent composite coating equipment control system designed in this paper can reduce energy consumption and pollution very well.

This article discusses a new type of vacuum equiaxed crystal precision casting furnace. The equipment is designed to replace the traditional vertical equiaxed crystal precision casting furnace for the production of thin-walled, large-sized and low-temperature casting parts. The furnace uses a series of innovative concepts and technologies such as horizontal layout, mould heater, coaxial water-cooled cable and coil motion devices. The furnace also has good scalability and can produce fine-grained castings by changing its functional parts.

Electron-beam based additive manufacturing(EBAM) technologies operate in vacuum chambers and possess the characteristics such as high energy efficiency and low residual stress, which makes them widely used in fields including aerospace and medical. This paper focused on two EBAM technologies of electron beam melting(EBM) and electron beam solid freeform fabrication(EBF³). The research and application progress of equipment, electron beam gun, processing technology,microstructure control were reviewed. Prospects on development of EBAM technologies were made.