The stringent high-vacuum requirement for scandate cathodes, leading to high costs and operational complexities, remains a critical bottleneck limiting their broader application in modern microwave vacuum electronic devices. This work systematically investigates the degradation mechanisms of scandate cathode emission performance in nonideal vacuum environments. Based on the test results of cathode emission current density decreasing with vacuum degree and conducting comparative assessments before and after atmosphere exposure, we separated the degradation mechanism into two distinct pathways: physical damage from ion bombardment and chemical property alteration from surface poisoning. The mechanisms were elucidated through a combination of surface morphology characterization in a scanning electron microscope (SEM), ion bombardment energy calculation via COMSOL/MATLAB simulation, and depth-profiling elemental analysis by argon ion sputtering-assisted X-ray photoelectron spectroscopy (XPS) of the cathode, combined with DFT calculations of the surface work function. The results show that the two damage pathways fundamentally disrupt the formation and stability of the surface dipole layer, impairing its ability to maintain low work function, which ultimately reduces the emission performance of the cathode. These findings provide valuable insights and a theoretical foundation for designing effective protection of scandate cathode emission performance.

Enhancing the performance of thermionic cathodes remains a persistent research objective. This work investigates a dispenser cathode impregnated with ZrO2-doped aluminate. Pulsed emission tests revealed a current density inflection point of $18.61 \mathrm{~A} / \mathrm{cm}^{2}$ at $1100^{\circ} \mathrm{C}$, with a slope of 1.4, indicating both high emission capability and good emission uniformity. Furthermore, the Miram curve and the Practical Work Function Distribution (PWFD) curve demonstrate that the cathode exhibits a work function of $1.86-1.88 \mathrm{eV}$, which is lower than that of conventional barium-tungsten dispenser cathodes.

Based on first-principles, this study investigates the effects of Al and In doping on the photoelectric properties of $2 D \beta-G a_{2} O_{3}$. The octahedral site is identified as the optimal doping position. The results show that Al doping increases the band gap to 2.273 eV, whereas In decreases it to 2.194 eV. Furthermore, both doped systems demonstrate a significant work function reduction of over 2.8 eV upon Cs adsorption activation, confirming their potential as next-generation photocathodes.

Vacuum microwave devices require cathode materials with high emission current density (>= 50 A/cm(2)) and long operational lifetime. To address issues of poor emission uniformity and limited reproducibility in Sc2O3-W mixed-matrix cathodes, this study introduces a mechanical fusion coating process. Using classified tungsten powder (average size: 3.8 mu m; span <= 1.2), a uniform W@Sc2O3 structure nano-Sc2O3 coating (100-290 nm) was applied. This method eliminated Sc2O3 agglomeration and yielded a sintered matrix with closed porosity <= 0.5%, a pore size of 0.6-1 mu m, and carbon content <= 400 ppm. At 1100 degrees C-b, the cathode achieved pulsed emission current densities of 149.86 A/cm(2) (1% duty cycle) and 81.36 A/cm(2) (5% duty cycle), representing a 108.1% improvement over planetary milled cathodes. The W@Sc2O3 increases specific surface area, supplying more active sites, while Sc2O3 migration to sintering necks enhances matrix stability. The uniform Sc2O3 distribution ensures consistent sintering shrinkage, enabling batch-suitable cathodes with high structural stability and machinability.

Dispenser cathodes for vacuum electron devices require higher current density and longer lifetime. To identify promising dopant elements that could enhance the cathode emission capability, first-principles calculations were performed to systematically evaluate the work functions of Ba0.25M0.25-O-W(001) (M = dopant). The results show that doping with Zr, Sc, Hf, Nb, and Ta reduces the work function by 0.404, 0.376, 0.289, 0.120, and 0.011 eV, respectively, compared with Ba-0.25-O-W(001) configuration. Furthermore, Zr doping on the W(112) and W(110) surfaces reduces the work function by 0.603 and 0.095 eV, respectively. Based on the result, ZrO2-doped aluminate dispenser cathodes were fabricated. Experimental evaluation shows that the 4 wt.% ZrO2-doped cathode achieves 17% and 29% improvements in direct current (DC) and pulsed emission current densities at 1050 degrees C over the undoped cathode, respectively. Its evaporation rate at 1050 degrees C is only 71% of that of the undoped cathode. Lifetime test results show that the emission current of the 4 wt.% ZrO2-doped cathode decreased by 4.7% with an initial current density of 3 A/cm(2) at 1000 degrees C after 1008 h, compared to a 10.7% decrease for the undoped cathode. Based on X-ray photoelectron spectroscopy (XPS) and first-principles calculations, Zr doping optimizes the Ba/O ratio on the cathode surface, thereby indirectly reducing the work function.

For long-life vacuum electron device applications, this study fabricated a coated W–Re matrix dispenser cathode. The W–Re mixed matrix was prepared through a three-step process: impregnation of porous tungsten with an ammonium perrhenate solution, thermal decomposition in a vacuum furnace, and reduction and sintering in a hydrogen atmosphere. The matrix was subsequently impregnated with 311-type aluminate and then coated with an Os film. Emission measurements revealed that the cathode achieves a DC emission current density of 10.12 A/cm2, and a pulsed emission current density of 40.2 A/cm2 ( $10~\mu $ s-100 Hz) at $1050~^{\circ }$ Cb. The effective work function derived from the Miram curve is 1.73–1.75 eV. The evaporation rate of the cathode is $4.90\times 10^{-9}$ g $\cdot $ cm ${}^{-2}\cdot $ s−1 at $1050~^{\circ }$ Cb. Consequently, in a DC lifetime test at $1000~^{\circ }$ Cb under an initial emission current density of 3.00 A/cm2, the cathode sustained continuous operation for 28 704 h, maintaining an emission current of 3.12 A/cm2 without degradation. First-principles calculations reveal that, compared with pure W(110), both Re(0001) and Os(0001) surfaces exhibit stronger Ba adsorption and a significantly lower sensitivity of the work function to variations in the Ba/O ratio, which contributes to improved emission uniformity and further prolongs the lifetime of the cathode.

Investigations on the scandia-doped impregnant have provided an effective way for optimizing cathode emission performance. In this paper, five sets of impregnant were obtained by sintering the precursor powders with different temperatures, and the impact of impregnant phase composition on the cathode emission performance was investigated. The results indicated that as the sintering temperature increased from 850 degrees C to 1200 degrees C, the ratio of c(Ba2ScAlO5)/c(Ba3Al2O6) in the impregnant and the coverage of scandium atoms on the activated cathode surface progressively increased, cathode surface work function initially decreased and then increased. When the c(Ba2ScAlO5)/c(Ba3Al2O6) = 0.92:1, cathode exhibited the highest emission property, with a pulse emission current density of this cathode is 523.2A/cm2 at 2000V under 1100 degrees Cb. The surface Ba:Sc atomic ratio of this cathode after activation was 1:0.9, and the surface work function was 0.95eV. In summary, the increasement in sintering temperature has a significant impact on c(Ba2ScAlO5)/c(Ba3Al2O6) in the impregnant, which in turn alters the atomic ratio on the activated cathode surface. When the surface Ba:Sc atomic ratio approaches 1:1, the cathode exhibits the best emission performance. While the cathode emission performance will gradually decrease as Ba atoms cannot be adequately replenished during cathode operation.

The backward wave oscillator (BWO) is an important vacuum electron source that utilizes backward waves to interact with electron beam, resulting in high-frequency self-excited oscillations. Due to the negative dispersion property, self-excited oscillations, tunability, room-temperature operation, and relativistic effects, the BWO has significant application prospects in fields such as terahertz (THz) imaging and nuclear fusion. The development direction of BWO is high frequency and high power. This article jointly reviews the research progress of THz BWOs in the last decade from many aspects, such as the theory of BWO, slow wave structure (SWS) design, and common fabrication methods used in the THz band, and introduces the latest methods and mechanisms for improving the performance of BWOs. In addition, the latest progress of relativistic BWOs (RBWOs) and the applications of BWOs was also introduced. The above contents will help to understand the theoretical and experimental studies of BWOs and RBWOs and promote their practical applications in the fields of identification imaging and energy.

The application of scandate cathode with high emission current density in microwave vacuum electronic devices is constrained by issues of poor emission uniformity and reproducibility. An effective strategy to enhance the emission performance of scandate cathodes is through the doping of additional elements. This article prepared yttrium-doped scandate cathodes and investigated the mechanism of yttrium affecting cathode emission performance via impregnant composition analysis, cathode emission property testing, surface element analysis, and density functional theory (DFT) calculations of surface work function and adsorption energy. As the yttrium content increases from 0 to 6 atom%, the total amount of aluminate compounds remains above 85%. The content of Ba2ScAlO5 in impregnant increased first and then decreased, while cathode emission property test results also increased first and then declined. The cathode with yttrium content of 3 atom% in impregnant has the best emission property, with an emission current density of 466.4 A/cm2 at 2000 V pulse voltage under 1100 degrees Cb, the practical work function of 1.64-1.68 eV. The theoretical surface work function of the ${x} = 3$ cathode is 1.67 eV, and the theoretical adsorption energy indicates a low evaporation rate on the surface of yttrium atoms during cathode operation. It can be inferred that the doping of yttrium has a visible impact on the composition of the impregnant. An appropriate amount of yttrium doping facilitates the formation of Ba2 ScAlO5 and enhances cathode emission properties, while superfluous yttrium inhibits Ba2ScAlO5 formation and results in an increased presence of BaY2O4 in impregnant, reducing the coverage of Ba atoms on the cathode surface, suppressing the enhancement of cathode emission performance.

Antimony sesquisulfide (Sb2S3) has emerged as a prospective and attractive material for next-generation solar cells due to its success in solution processing, high stability, low toxicity, and exceptional optoelectronic properties. Exploring the growth properties of Sb2S3 films is imperative to further improve the power conversion efficiency (PCE). In this investigation, Sb2S3 films were effectively produced through the application of electron beam evaporation, which was subsequently followed by post-annealing treatment. The impact of annealing temperature, duration, and target weight on crystalline orientation, morphology, internal stress, and optical characteristics were examined. The films exhibited a pure orthogonal phase with strong [hk0] crystalline orientation, uniform surface, and large grains after the annealing process. The Raman spectrum analysis demonstrated that sulfur loss in films escalates with increasing annealing temperature and time. The stress in the (hk1) and (hk0) planes increases with the increase of film thickness, and the stress in the former is greater than that of the latter. The synergistic effects of the electron beam evaporation technique and subsequent postannealing treatment further illustrate the promising potential of Sb2S3 for use in solar cells.

In this paper we mainly describe the research progress of oxide cathode and its application in vacuum electron device, which includes a Ni-Sc sponge oxide cathode, a reservior oxide cathode, and a NiMoFe alloy direct-heated oxide cathode.

The temperature uniformity of the cathode of the magnetron injection electron gun were analyzed by ANSYS software, and the steady-state temperature distribution of the cathode emission belt of the electron gun was obtained. By selecting the appropriate heating power to reach the working temperature, and optimizing the slotting parameters of the rear focusing electrode of the electron gun, the temperature difference of the cathode emission belt is reduced to 3.2°C.

Based on the development of a magnetron injection electron gun（MIG） for gyrotron oscillator operating at 140 GHz and with about a megawatt output power, the temperature homogeneity of the cathode and thermal deformation of the MIG were analyzed with ANSYS code. Under an improved temperature homogeneity of the cathode, the geometrical and electrical parameters have been adjusted and optimized to eliminate the effect of thermal deformation on beam trajectory. The simulated temperature of the cathode will be compared with the tested one for evaluating the rationality of the simulation model, which may be helpful for the actual design.

多孔金属材料是一类具有优异性能的新型材料.本文首先简述了多孔金属材料的几种常用制备方法及应用领域.然后对多孔钨材料在微波真空器件、核聚变及空间电推进技术等领域的应用进行了介绍,指出了多孔钨材料及零件制备中存在的问题,针对这些问题对多孔钨材料及零件制备工艺进行了深入研究.利用射流分级技术对钨粉进行了分级,激光粒径测试仪的分析结果表明,分级后的钨粉颗粒度分布更加集中.采用气体纯化装置对烧结用氢气中残余的水和氧进行了净化,使氢气的露点从纯化前的-50℃降到纯化后的-90℃以下,为制备出无氧化的多孔钨材料及零件提供了很好的烧结环境.利用冷等静压技术和高温烧结技术制备出多孔钨材料,压汞仪分析表明钨粉分级使多孔钨材料的比表面积增大,闭孔率大大降低,孔度更加均匀一致.采用真空浸铜的方法制备出多孔钨铜合金材料,与传统氢气浸铜方法相比,真空浸铜的浸渍率提高了4％以上.采用真空去铜法净化了多孔钨铜零件,结果表明该方法具有处理时间短、去铜彻底、对环境无污染等优点.

Recently, significant breakthroughs in power conversion efficiencies (PCEs) have been obtained for 3D CsPbI 3 -based perovskite solar cells. In the present work, a novel heterojunction structure with 1D Sb 2 S 3 as the hole transport layer was designed and investigated using solar cell capacitance simulator simulation software. The influence of thickness, band offset, conduction type, doping concentration, bulk and interface defect densities on the performances of the devices were analyzed. The PCE of the devices increases with the increase in the thicknesses of the CsPbI 3 and Sb 2 S 3 layers. The p -type conduction of the CsPbI 3 under-layer has more advantages with regard to broadening of the doping density, and the higher acceptor density in the Sb 2 S 3 over-layer contributes to the improvement of the performance of the device. In addition, the device performance is more sensitive to the defect density at the CsPbI 3 /Sb 2 S 3 interface than that in the Sb 2 S 3 over-layer. Finally, a PCE over 20% is obtained for the device with optimal parameters. These simulation results demonstrate the tremendous potential of a novel 3D/1D CsPbI 3 /Sb 2 S 3 heterojunction design for high-performance and high-stability devices.

In order to prolong the service life and high-temperature stability of direct-heated cathode, a novel cathode is proposed and prepared, in which La2O3, Gd2O3, and HfO2 are used as raw materials for the first time. The X-ray diffraction (XRD) structure characterization shows that emission material consists of La2O3 and La2Hf2O7 two compounds. The thermionic emission results indicate that this kind cathode can supply a current density of about 5.5 A/cm2 at 1600 °C. The energy dispersive spectroscopy (EDS) detection manifests the emission material distributes homogeneously around the W–Re base. The cathode has been working stably for 10 920 h without obvious fall at 1550 °C with the loading of 0.65 A/cm2 in life test process.

The RF shield bellows of storage ring is composed of circular structure and circular main body with slit structure. For every shield finger there is a mating spring finger that exerts $123\pm 25$ grams of contact force. The surface of SS stube and spring finger is silver plated with a thickness of $5-10\mu m$ . The silver plated spring finger has a good self-lubricating function. The spring finger, contact finger and SS stube form a good friction structure. The internal ultra-high vacuum degree of the shield bellows is better than $1.6\times 10^{-10}Torr$ , and the vacuum leakage rate of the weld and the shield bellows is better than $1\times 10^{-11}\ Torr-L/s$ .

Os-coated barium-tungsten dispenser cathodes have attracted attention due to their low operating temperature, high current density and long lifetime. The tungsten in the substrate will continue to diffuse into the coating during the working process of the coated barium tungsten cathodes. In order to investigate the effect of Os coating on the emission performance of Ba-W dispenser cathodes, the work function of Os surface, Os-O-Ba surface, Os3W-O-Ba surface and W (Some atoms are replaced by Os atoms) - O-Ba surface were calculated by density functional theory (DFT). And the influence of Os on the emission properties of impregnated barium tungsten cathodes is discussed by the calculation results.

As the performance of the vacuum electron devices largely depends on the properties of their cathodes, developing efficient and durable thermionic cathode is necessary and highly desired to meet the boosting requirements of the vacuum electron devices. This paper mainly describes the research progress in W-Re base direct-heated cathodes used in high-power continuous wave magnetrons, which include the $\boldsymbol{Sc_{2}O_{3}}$ doped Y-Gd-Hf-O pressed series cathodes and the $La_{2}Hf_{2}O_{7}$ cathode. The current density of the pressed Y-Gd-Hf-O cathode can remain to 87.5% of the initial one after continuous electron bombardment for 480 $\boldsymbol{h}$ , and the best emission ability of 2.79 $A/cm^{2}$ has reached with the 5/2 molar ratio of the $\boldsymbol{Y_{2}O_{3}/HfO_{2}}$ at $1500^{\circ}C$ . The lifetime of the $\boldsymbol{L_{2}Hf_{2}O_{7}}$ cathode is beyond 10000 $\boldsymbol{h}$ at $155\theta{\ }^{\circ}C$ with the loading of 0.65 $A/cm^{2}$ .

本文总结了用于真空微波电子器件的浸渍阴极的蒸发规律,通过分析提出了浸渍阴极预处理工艺,建立了超高真空装置.在超高真空环境下,将浸渍阴极灯丝加热,使阴极温度升高到1100～1200℃,保持1～200h(温度和时间依不同微波管型而定).预处理工艺解决了浸渍阴极发射与蒸发的矛盾,现已建立数十台、几十个工位的浸渍阴极预处理设备,大大提高了微波真空电子器件中电子枪的绝缘性能,减小了栅发射.浸渍阴极预处理工艺还可以加速检验热子的可靠性,从而避免微波器件在使用过程中才发现热子短路、热子缺陷及热子焊接点不牢等因素造成热子断路的问题,提高了微波真空电子器件中热子的可靠性.