HEPS （high energy photon source） is the 4th generation ring-based light source with a beam energy of 6 GeV and a beam current intensity of 200 mA. The HEPS accelerator consists of a linac, a booster, a storage ring, and three transport lines connecting them together. The storage ring serves as the core region of HEPS. In this paper, the characteristics of the storage ring vacuum system are reviewed, and the design and fabrication approach for some key vacuum components are detailed. The main challenges include extruding thin-walled CrZrCu vacuum chambers and coating NEG films on their inner surfaces. These are used to mitigate substantial heat loads induced by synchrotron radiation along the vacuum chamber walls and provide an effective pumping speed for conductance-limited vacuum pipes with an inner diameter of 22 mm. At present, the procurement of all the vacuum components has been completed. The installation of the storage ring vacuum system started in November 2023, and finished in July 2024. Vacuum sectors were baked and activated in-situ for the NEG films inside the vacuum chambers, an average static pressure of 5×10^-8 Pa has been reached, which is better than the specification. The results verify the feasibility of the storage ring vacuum system from the design and fabrication of vacuum chambers, RF shielding bellows, photon absorbers, etc. to NEG coating with magnetron sputtering, installation, activation of NEG films in-situ, etc. After more than 20 days of conditioning, the beam current of the HEPS storage ring reached 12 mA, marking a milestone progress in the HEPS accelerator.

Based on the current research progress of laser additive manufacturing technology on superalloy at home and abroad, the preparation methods of superalloy powders and the influence of recycling and reuse on powder properties are reviewed. The application of simulation calculation technique in superalloy additive manufacturing process and material design is discussed. The common defects and optimization methods of additive manufacturing of superalloy are summarized. Finally, the standardization process of superalloy additive manufacturing is introduced.

Vacuum insulation panels （VIP）, as a new type of insulation material, have been widely used in various industries. However, the existing chopped strand glass fiber core material VIP has the problems of high rebound rate and low service life, which limits its further development. Therefore, a particle-modified composite VIP with excellent comprehensive performance was prepared by adding nano fumed silica particles to the core material for modification. The microstructure, uniformity, compression rate and rebound rate of the as-prepared composite core material were tested, and the thermal conductivity and pressure sensitivity of the prepared VIP were studied. The results show that the particle modified composite VIP has excellent comprehensive performance, accompanied by a fumed silica particle mass fraction of 0%-15%. With the increasing of fumed SiO₂, the compression rate decreases from 63.9% to 53.2%, and the rebound rate decreases from 74.9% to 64.3%. At the same time, the pressure sensitivity of VIP also shows a downward trend.

In order to ensure the stability and optimize the bonding properties of ceramic tile adhesives, the preparation method with vacuum technology and properties of new material ceramic tile adhesive combined were studied. The concrete surface test blocks for tile bonding according to standard tile sizes were prepared, and waterproof materials were applied to them according to indoor decoration construction scenarios. Ceramic tile adhesive prepolymer was prepared by vacuum synthesis of potassium hydrogen phthalate and toluene diisocyanate. The adhesive prepolymer was modified through Michael addition reaction to reduce biological toxicity. A vacuum drying oven was used to dry the modified adhesive prepolymer, regulating the drying process to obtain the initial adhesive product. Vacuum drying oven and circulating water vacuum pump were used to eliminate water and air interference, ensuring that the adhesive can be prepared completely in the vacuum stable state. The experimental results indicate that the Fourier transform infrared spectrum of the adhesive contains a large number of azide groups and has low biological toxicity. The contact angle between the adhesive and the surface of ceramic tiles and concrete is less than 90°. When the strain is 8%-11%, the mechanical property of the adhesive is better. When the environment temperature is below 180 ℃, the thermal stability of the adhesive is better. The application of the newly prepared ceramic tile adhesive in the field of indoor decoration construction is relatively environmentally friendly. In a vacuum stable state, the interaction between the adhesive and ceramic tile molecules is less affected by air and water molecules, and the adhesion performance is better.

Aiming at the problem that the inlet flow of large-scale centrifugal vacuum pump is difficult to distribute uniformly in parallel operation in confined space, the aerodynamic analysis of four-way and five-way inlet pipes of centrifugal vacuum pump is carried out by numerical simulation analysis. The aerodynamic structure with uniform inlet flow, small flow pressure loss and uniform flow distribution is obtained, and it is verified by practical application. The results show that the strategy of dividing intersecting cone into two and then dividing into four is an effective four-way and five-way diversion strategy in confined space. Under the condition that the length of the front and rear air inlet paths is quite different, it is difficult to meet the flow uniformity and flow resistance matching at the same time, so the rectifier is designed to match the flow resistance difference. The practical test results of pressure difference between the main pipeline and inlets of optimized pneumatic structure and their flow rate are consistent with the calculated results, indicating that the design method is effective and feasible.

A set of design methods suitable for the vacuum chamber of a square electron beam melting furnace is proposed to address the difficulties in selecting the wall thickness and reinforcing ribs. The method first confirms the furnace material for the vacuum chamber, and arranges reinforcing ribs according to the hole positions such as flanges, openings and exhaust holes, and calculates the wall thickness. Taking the rectangular reinforcing ribs as example, the calculation methods for the wall thickness, the maximum bending moment of the plate between the reinforcing ribs, inertia moment, section modulus in bending and shear stress on the neutral layer during bending of the square vacuum chamber under conditions of bearing water pressure and air pressure were discusses in detail. Finally, the as-designed vacuum chamber of the electron beam melting furnace was validated through simulation experiments. The results indicate that the stress of the vacuum chamber of the as-designed electron beam melting furnace under water and gas load conditions is within 35 MPa, which is lower than the allowable stress of the material. The calculation results of this method are highly consistent with the simulation results, it can meet the design requirements of vacuum chambers similar to square electron beam melting furnaces.

Miniaturized high-power multi beam klystron is an ideal power source for electron linac for NDT, medical and industrial irradiation. This paper briefly introduces a new C-band 3 MW miniaturized high-power multi beam klystron developed by Beijing Vacuum Electronics Research Institute. In order to achieve high power and miniaturization performance of the device, technologies such as transverse coupled coaxial cavities, period permanent magnet system, half wavelength box shaped energy transmission window are used and described. The device test results show that the peak output power is greater than 3.3 MW, the average power is greater than 6.6 kW, and the mass is less than 25 kg, which can meet the requirements of industrial accelerators, and a series of C-band products with output power from 1 MW to 5 MW may be formed.

Vacuum technology is widely used in the field of nuclear industry. When dealing with vacuum devices containing radioactive and toxic and hazardous substances, it is particularly prudent to operate and maintain them, which usually need to be placed in a hot cell. In order to realize the effective operation and easy maintenance of the vacuum device, and improve the reliability of the vacuum device, it is particularly important to carry out adaptive design. Based on the basic background of the hot cell, this paper introduces the design points of the key elements such as the automatic sliding door of the vacuum equipment that can be operated remotely, the vacuum system arranged remotely outside the hot cell, the metal vacuum sealing, the motor structure that can be replaced remotely, and the selection of radiation-resistant materials, which provides scientific basis and practical guidance for the design of similar vacuum devices.

The chemical and physical changes of plasma degluing and cleaning are briefly introduced. The factors that determine the degluing effect and uniformity are analyzed systematically, and the corresponding scheme and the optimal parameter matching principle are given. The optimal removal process parameters of micro and nano scale Ar-F photoresist under different process conditions were studied through experiments, and several groups of process parameters with good degluing effect were obtained. The reaction principle and process of plasma cleaning, and the application of plasma cleaning in surface modification of materials are discussed.

Indium tin oxide （ITO） transparent conductive oxide films were prepared on high temperature resistant quartz glass substrates by radio frequency （RF） magnetron sputtering technology, aiming to optimize their photoelectric properties. By systematically regulating the sputtering power variable, the influence mechanism of this parameter on the quality and photoelectric properties of ITO films was deeply analyzed. Then, the films were annealed to explore the change of film properties before and after annealing. The results show that with the increase of sputtering power, the average transmittance of visible light of ITO film shows a decreasing trend, while the sheet resistance of the film shows a trend of decreasing first, then increasing and then decreasing. When the sputtering power is set to 120 W and annealed at 300 ℃, the prepared film has the best comprehensive performance : the average transmittance of visible light reaches 90.59%, the square resistance is as low as 29.4Ω/□, and the quality factor reaches 1.26×10^-2 Ω^-1.

The principles and characteristics of the plasma ion assisted deposition （PIAD） method are described, in which ions generated by ionizing raw material gas by high-frequency discharge are implanted into a base material to which a high voltage pulse voltage is applied. The characteristics and application examples of the diamond-like carbon thin film （DLC thin film） formed by PIAD method are introduced. The PIAD method can control the growth of the sp2-structured graphite layer and the sp3-structured diamond layer in the DLC thin film by pulse voltage and other film-forming conditions, so the DLC thin film that exhibits corrosion resistance and conductivity can be formed. The results of the development of functional DLC thin film prepared by the PIAD method in surface treatment for the metal separator of the fuel cells are introduced emphatically.

To explore the influence of different types and additive amounts of alloy elements on the morphology, composition, and distribution of inclusions in Q355B steel, different amounts of elements （Ti, Zr, Mg, and Ce） were added individually employing the method of vacuum induction melting. Spectral analyzer, scanning electron microscope, energy dispersive spectrometer, and image analyzer were used to observe and analyze the composition and morphological characteristics of typical inclusions in Q355B deoxidized steels. The results indicate that the addition of deoxidizing elements promotes the presence of MnS in Q355B steel in the form of composite inclusions. MnS+TiN/Ti-O/Al-Si-O, MnS+ZrO₂, MnS+Al-Mg-O and MnS+Ce₂O₃ were formed in Ti-, Zr-, Mg- and Ce-deoxidized steels, respectively. Proper control of the amount （mass fraction）of deoxidizing elements can achieve better control of inclusions. Oxides of Ti or Ce have a better refinement effect on the size of MnS inclusions, while excessive amounts of Zr or Mg can lead to the aggregation of ZrO₂ or the formation of MgO+SiO₂+MnO composite inclusions, resulting in the formation of coarse inclusions. Additionally, the reasonable range of elemental addition for Q355B steel when using single deoxidizing elements is preliminarily determined. 0.010%Ti, 0.005 2%-0.008 8%Zr, 0.003 2%Mg, and 0.007 1%-0.008 8%Ce are more conducive to the stability of inclusion size as well as the microstructure refinement in Q355B steel.

With the continuous development of China's commercial aviation engine industry, the demand for large-sized casing castings is increased. Facing the complex international environment, large vacuum induction precision casting furnaces, as the core equipment for producing large-sized casings, must break free from import dependence. This article first conducts an in-depth analysis of the market situation and technological status of large-scale vacuum precision casting furnaces. Then the technical characteristics of the domestically produced new large-scale vacuum precision casting furnace and the comparison with foreign products are introduced. Finally, a brief analysis is conducted on the future development prospects of the large vacuum precision casting furnace.

A series of nickel based superalloy samples with different P contents were prepared by vacuum induction melting and atmosphere protection electro slag remelting. The effect of P element on the microstructure and mechanical properties of the alloy was systematically analyzed using advanced characterization techniques such as optical microscopy, scanning electron microscopy, electron probe microanalysis, Vickers hardness tester, and tensile testing machine. The results show that the grain structure and γ' phase of the as cast alloy with different P contents have no significant change. With the increase of P content, the density of carbides at the grain boundaries increases, and the morphology of carbides changes from point like to short rod-shaped. The segregation of P element at grain boundaries reduces grain boundary energy, decreases the critical nucleus size for carbide, thus promoting the precipitation of carbides. In addition, as the P content increasing, the hardness, impact toughness, and tensile strength of the alloy increase, while the elongation decreases. Carbides at grain boundaries can effectively hinder the propagation of cracks, causing them to deflect and shift from the grain boundaries to the interior of the crystal, thereby significantly improving the comprehensive mechanical properties of the alloy.

The effects of different aging temperatures (540-620 ℃) on microstructure and mechanical property of ZG0Cr17Ni4Cu3Nb and 0Cr17Ni4Cu4Nb precipitation-hardened martensitic stainless steels were studied by vacuum aging treatment. The results show that the hardness of both materials decreases with the gradual increase of aging temperature. Under the same aging conditions, the hardness of 0Cr17Ni4Cu4Nb is better than that of ZG0Cr17Ni4Cu3Nb. The increase of aging temperature promotes the recovery and recrystallization of quenched martensite matrix, and reverse austenite gradually forms and expands, resulting in the increase of retained austenite content and microstructure softening. In addition, the precipitation and growth of precipitated phase particles such as copper-rich phase (ε-Cu) weaken the precipitation strengthening effect and further aggravate the decrease of hardness.