As an important component of the helium mass spectrometer leak detector, the geometric parameters of the composite molecular pump not only affect the pumping performance, but also affect the detection performance of the leak detector. Based on the basic theory of molecular pump pumping, this paper establishes the calculation model of composite molecular pump turbine stage. By changing the blade inclination, blade number, blade height and blade thickness, the pumping performance of composite molecular pump turbine stage to air and helium was calculated respectively, and the influence of composite molecular pump turbine stage parameters on the detection performance of helium mass spectrometer leak detector was studied. The results show that reducing the blade inclination, increasing the number of blades, the blade height and blade thickness are conducive to the improvement of the detection sensitivity of the helium mass spectrometer. Considering the pumping performance of molecular pump and the detection sensitivity of helium mass spectrometer, the optimal blade inclination is 25°, the number of turbine blades is between 25 and 30, the blade height is 3 mm, and the blade thickness is 0.6 mm to 0.8 mm.

Manned spacecraft hatch is the aisle for astronauts and cargo to enter and leave the sealed capsule of spacecraft. Once leakage occurs, it will affect the normal operation of manned spacecraft, and even threaten the life safety of astronauts. In order to ensure the sealing performance of manned spacecraft hatch, strict leak detection tests must be carried out before launching. In view of the special structure of manned spacecraft hatch, this paper mainly introduces the leak detection methods for hatch body and frame sealing ring, the whole hatch and the part of hatch. It forms a set of leak detection technology suitable for the whole development process of manned spacecraft hatch, which can meet the leak detection requirements of manned spacecraft hatch, such as Shenzhou spacecraft, space station, lunar module and so on.

Through the calibration chamber and vacuum tube installed on the intake pipe of the mass spectrometer, the trace gas with the same content range as the gas in microsphere can be obtained. The precision of quantitative analysis of trace gases by mass spectrometer and the effect of measured deuterium pressure on the calibration factor of D₂ were studied. The results show that the precision of the quadrupole mass spectrometer is high, and the relative standard deviation of the 10 repeated measurements under different pressures is less than 0.004. The mass spectrometer has a high stability within one month after calibration, and it has a high accuracy with the quantitative analysis error is less than 1%. The concentration calibration factors for D₂ and Ar varied no more than 3% within one year, while the pressure calibration factors for D₂ varied more than 8% within one year. The pressure calibration factor η of D₂ is inversely proportional to the pressure P₁ of the measured deuterium gas, and there is a good linear relationship between η and logP₁, which has a high stability in half a year.

In this paper, methods and principles of detection for the small leaks of the missile-borne klystron is described in detail. Firstly, the process of the pressurization detection method is clarified, some key parameters(such as helium storage pressure, storage time, characterizing parameters of the vacuum degree in the device) are theoretically calculated and analyzed, and results with guiding significance are obtained. Secondly, the main device components are described in detail. Finally, the pressed storage experiment of the missile-borne klystron is carried out in the equipment. The experimental results show that the equipment can efficiently eliminate the unqualified components, which meets the expected requirements, and the customer feedback is good.

The beam power of the CSNS II accelerator will be upgraded from 100kW to 500kW, which requires the average beam power of the linear accelerator to be increased from the current 5kW to 25kW, and the pulse beam intensity to be increased from 12.5mA to more than 40mA. For this reason, the Penning type surface negative hydrogen ion source currently in use will be replaced by a radio frequency（RF） negative hydrogen ion source. Considering that the beam cutting ratio of the beam chopper ranges from 35% to 50%, and the LEBT transmission rate can reach 75% to 95%, the RF negative hydrogen ion source needs to produce a negative hydrogen ion beam of at least 50mA. Therefore, the hydrogen gas consumption of the ion source needs to be increased from the current 10sccm to more than 20sccm,and the pressure of LEBT second chamber is required to be ≤5.0×10^-3Pa. Based on this, the ion source and the LEBT vacuum system are modified in this paper,and the beam transmission rate of LEBT is improved. In addition, the pumping speed of hydrogen with two domestic and imported magnetic levitation molecular pumps is compared,which provides a certain reference for the selection of molecular pumps and localized substitution.

Screw vacuum pump is widely used in semiconductor, coating, chemical and other industries owing to its ideal performance. The inner compression screw vacuum pump begins to compress the working gas during the gas delivery stage and has a series of outstanding advantages. This paper divides the internal compression screw rotor into two types of variable pitch and variable section,and the relevant research progress of their mathematic model design, performance analysis method and dynamic balance calculation is introduced respectively, which can provide a reference for the theoretical research of internal compression screw rotor.

The transition flow is solved by the joint calculation of NS and DSMC methods. The NS/DSMC coupling method has the advantages of the computational efficiency of NS method and the computational accuracy of DSMC method.In this paper, the principle of key technologies in the development of coupling method is introduced in detail, the application progress of coupling method in spatial plume research is discussed, and the shortcomings of computational domain partition method are explained. Then the application of coupling technology in the flow around neighbor spacecraft is analyzed. It is proposed that the error between the coupling calculation and the experimental results may be caused by DSMC statistical scattering, which can be eliminated by cumulative statistics. In addition, the application of NS/DSMC coupling method using two-phase flow model in MEMS field is also discussed. Finally, the application of coupling method in vacuum field and the research direction of coupling algorithm in the future are prospected.

The thermal expansion and oxidation resistance of bond coating alloy are closely related to its phase structure, which directly decide the reliability of thermal barrier coating and the service life of turbine blade.In this work, the equilibrium phase structure, the microstructure and element distribution under non-equilibrium condition, the coefficient of thermal expansion(CTE)variation versus temperature, and the isothermal oxidation behavior at 1100℃ of the NiCrAlYSi bond coating alloy were comprehensively investigated by using thermal dynamic calculation and experimental analysis. The results show that the main equilibrium phase constituent is FCC_L12 γ′-Ni₃Al phase, combined with some BCC_B2 α-Cr and β-NiAl at room temperature.When the temperature reaches 870℃, the equilibrium phase changes to β-NiAl and γ-Ni. The non-equilibrium microstructure consists of γ-Ni+β-NiAl. Moreover, the α-Cr and γ′-Ni₃Al precipitate in the β-NiAl matrix and the γ-Ni phase is surrounded by the γ′-Ni₃Al. The element Si primarily solid solutes in γ′-Ni₃Al phase and Y mainly exists in the form of Ni₅Y, both of which are distributed at grain boundaries. The CTE(×10^-6K^-1) is increased from 11.9±0.17 to 20.5±0.13 as the temperature increases from 100℃ to 1200℃, and the increasing rate is obviously larger at the temperature higher than 900℃. The oxidation layer with the poor continuity and density is obtained, which is separated from Al depletion zone. When the oxidation time prolongs from 20h to 100h, the thickness of the oxidation layer increases from (1.70±0.072)μm to (3.28±0.275)μm, and the Al depletion zone thickness increases from （7.48±0.606）μm to（10.67±2.654）μm, respectively. The average weight gain gradually increases from 0.608g·m^-2 to 3.623g·m^-2. The average oxidation rate first decreases from 0.030g·m^-2·h^-1 to 0.020g·m^-2·h^-1, and then increases to 0.036g·m^-2·h^-1, of which the minimum value is obtained at 60h.

This paper introduces an ion beam assisted deposition surface modification technology combined with ion implantation and vapor deposition film based on general vacuum winding aluminum plating machine. By adding a set of auxiliary bombarding ion source on ordinary winding plating equipment to establish an ion assisted deposition system, transparent alumina membrane plating can be realized. The equipment structure, characteristics and working principle of this coating method are described, the application prospect of this coating method is presented. Aluminized film plating can also be realized on the equipment, breaking through the single response of ordinary aluminum-based coating types. This technique responds to the national call for the realization of the localization of aluminum oxide evaporation coating equipment.

To address the problems of low deposition rate and uneven film thickness in the preparation of SiC films by pulsed laser method and sublimation method, this paper adopts the vacuum DC magnetron sputtering technique to deposit SiC films on the surface of flat glass substrate using a SiC target with high carbon content. The effects of different parameters on the deposition rate and film thickness uniformity were investigated by varying the DC power and sputtering pressure. The thickness, cross-sectional morphology and Si, C content of the films were characterized by step meter, scanning electron microscope（SEM）and energy spectrometer（EDS） respectively to obtain the optimal process parameters. The experimental results show that the film deposition rate reached 15.39nm·min^-1 when the sputtering power was 2000W under the same sputtering air pressure condition.The variation coefficient of thickness uniformity of the deposited films was within 3% while the film deposition rate reached 10.67nm·min^-1 when the sputtering air pressure was 0.8Pa under the same DC power condition. In addition, the films prepared by DC magnetron sputtering were dense and porosity-free inside,and the Si, C content was above 99%.

Aluminide coating was deposited on the nickel-based single crystal superalloy DD5 by chemical vapor deposition(CVD), then NiCoCrAlYHf(HY5) metal bond coat was deposited in situ by vacuum arc ion plating(ARC), and yttria-stabilized zirconia(6~8YSZ) was deposited by electron beam physical vapor deposition(EB-PVD). The isothermal oxidation protection performance of DD5+(HY5+YSZ) and DD5+(Al+HY5+YSZ) samples at 1100℃ was compared. X-ray diffraction, scanning electron microscope and electron probe methods were used to analyze the evolution of microstructure and composition of the two coatings during high temperature oxidation. The results show that DD5+(Al+HY5+YSZ) coating has a dense multi-layer structure and combines well with the substrate. After isothermal oxidation for 250h, the appearance of the two coatings both keep intact. During the isothermal oxidation process at 1100℃ for 250h, the oxidation rate constants of DD5 alloy, DD5+(HY5+YSZ) coating, and DD5+(Al+HY5+YSZ) coating are 0.415, 0.410, 0.354g²·m⁴·h^-1, respectively. After isothermal oxidation for 250h, the highest Al contents in DD5+(HY5+YSZ) and DD5+(Al+HY5+YSZ) coatings are 5.8wt% and 16.7wt% respectively, which is in good accordance with Al content on the bond coat upper surface of 3.7wt% and 6.0wt%, and the thicknesses of thermal grown oxide(TGO) are 6.6μm and 9.4μm respectively. Element interdiffusion occurs between two coatings and the substrate,leading to the appearance of secondary reaction zone(SRZ). The SRZ in the DD5+(Al+HY5+YSZ) coating is more obvious and continuous than that in DD5+(HY5+YSZ).

Low-carbon development of metallurgical industry with high energy consumption and high carbon emission has become the consensus of the international community and industry under the background of carbon emission peak and carbon neutrality. As one of metallurgical industries with the largest carbon emission per unit product, carbon emission reduction of magnesium production is imperative. Developing new low-carbon magnesium production technology is the way forward. This paper analyzes the shortcomings of the Pidgeon process and introduces the principle and advantages of the new aluminothermic reduction methods of magnesium production. The results show that the Pidgeon process has the disadvantages of large raw material consumption, high energy consumption and large carbon emission. Limited by the reduction principle of magnesium production, it is difficult to further reduce the energy consumption and carbon emission. Compared with the Pidgeon process, the aluminothermic reduction process has the advantages of less raw material consumption, high production efficiency, low energy consumption and zero discharge of waste residue, and the carbon emission of which can be reduced by 30%-50%. The aluminothermic reduction process with a lowcarbon emission and pollution-free green magnesium production process has a good application prospect under the background of carbon emission peak and carbon neutrality.

This paper discusses the common structure and future development direction of vacuum induction furnaces.First of all, the characteristics of different structural furnace types are introduced. Then the overview of various furnaces in the current mainstream market environment is analyzed. Finally, the future development direction of vacuum induction furnaces is predicted through the comparison and analysis of technology and market conditions.

Microwave vacuum electronic devices are used in a wide variety of areas such as radar, space technology and electron accelerators. The heater assembly is one of the cores for the vacuum electronic devices. Their performances directly determine the reliability and lifetime of the electronic devices. A strategy to develop a new type of method for heater assembly is proposed in order to overcome the shortcomings of traditional heater assembly preparation process. High temperature vacuum sintering technology is used to melt the heater and the insulating material together, which improves the compactness of the heater assembly, reduces the adsorption of residual gas, enhances the impact resistance of the heater assembly, and overcomes the shortcomings of brittleness of the heater.

The intravehicular activity space suit is an important guarantee for astronauts to sustain life in the case of pressure loss in the cabin. The thermal comfort of astronauts is one of the important factors to be considered in the long time pressure loss condition. Based on the lumped parameter method, the thermal model of the spacesuit in the cabin is established, and the human-spacesuit thermal model is established with the Fiala model. The correctness of the simulation is verified by the domestic experimental data. Based on the simulation, the change rules of thermal comfort and humidity of ventilation gas under different pressure loss conditions were obtained, and the system optimization scheme was put forward, which provided reference for the design of emergency cabin pressure protection system and the formulation of life protection scheme in China.