利用离子束辅助沉积技术在Ba-W阴极表面上分别沉积金属钼膜和铪膜,以模拟栅控行波管中钼栅极和铪栅极表面吸附阴极蒸发物质时的表面状态.研究了这两种栅极表面微观结构和成分的变化,并测试了其表面热电子发射能力和二次电子发射系数.实验结果表明,铪栅极表面吸附的阴极发射物质要远少于钼栅极,用金属铪作栅极材料能有效抑制栅极电子发射.

In this paper, in order to estimate the life of TWT quickly, an accelerated degradation test (ADT) was carried out applying a short vacuum tube, and a life prediction method based on the Wiener-Arrhenius model is proposed considering individual variability among the tested samples. The validity of the proposed method is verified through comparison with the extrapolation result of curve fitting under normal operating condition, and it is concluded that the Wiener-Arrhenius-model-based method is more accurate and reliable.

A high-efficiency optical method was developed to solve the problems of measurement inefficiency and instability in the helix of a traveling wave tube (TWT). This method offers several improvements over existing methods. First, a device for helix placement and adjustment based on double standard bar rolling was chosen to make the rotation angle of the parts controllable and the placement straightness within 0.01 mm. Second, a linear viewfinder was used to effectively increase the stability of the automatic edge finding process by avoiding burr and overturn interference; the repeatability of the measurement results was better than 0. 8 mu m. Next, a port inner diameter measurement setup based on a 45 degrees rectangular prism was developed to obtain a distinct contrast imaging effect, and the helix's outer surface roughness was measured using a laser confocal microscope; the measurement results were in good agreement with those in process law. Finally, high efficiency and flexibility was achieved by applying a segmented array programming strategy and intersection distance algorithm for the detection of the stepping pitch helix; the detection time for a single helix reduced to one-third that of the existing method. These results arc of great significance for improving the qualification rate of helical TWT products and realizing their batch production.

为了对行波管寿命进行快速预估,利用行波管短管在地面开展了加速退化试验.考虑到施加不同应力引起产品的退化率不同,提出了基于Wiener-Arrhenius模型的寿命分析方法.首先,以行波管阴极的发射电流为性能退化量,通过温度加速退化试验获取其阴极发射电流退化数据;然后利用Wiener过程描述行波管阴极的退化过程,使用Arrhenius模型分析样本退化量与阴极工作温度之间的关系;最后使用极大似然估计和最小二乘法,估计行波管阴极在正常工作条件下的模型参数,并对该型行波管阴极在正常工作条件下的寿命进行预估.与正常工作温度条件下利用Wiener过程模型和阴极发射电流退化数据拟合的结果进行对比,表明了本文中模型的正确性和预估结果的合理性.

为解决EAST PF8线圈氦管在与导体连接的焊缝位置出现的泄漏问题,分析了该氦管的载荷及边界条件,给出了4种载荷组合工况.建立PF8氦管的有限元模型,对4种工况进行了静力学分析.计算结果表明,热载荷和螺管固定支撑板G11变形是焊缝失效的主要原因.在4.5K下对PF8氦管样件进行了疲劳试验,结果表明氦管疲劳寿命超过2×105次,满足使用要求.对PF8氦管进行了修复,使氦管与螺管固定支撑板G11板脱开,避免了额外载荷的作用,满足EAST使用要求.

通过对不同Mo-Mn金属化配方体系的烧结镍工艺探索,发现烧结镍工艺适用于Mo含量高的Mo-Mn金属化配方体系.当Mo质量分数为70％时,镍粉粒度d0.5为1.872 μm,镍层厚度为6～12 μm时,封接件断面显示镍层连续、致密,陶瓷标准件的抗拉强度为116 MPa,陶瓷金属封接件的环境性能测试结果符合行业标准要求.

The highly purespongy tungstendisc,widely used as impregnated dispenser-cathode in microwave vacuum electronic devices,was fabricated by high (mid) frequency induction heating of W-Cu alloy in the vacuum reactor with a water-cooled condenser.The impact of heating temperature and time on porosity and purity of the spongy W-disc was investigated.The results show that the highly clean and pure spongy W-disc can be fabricated by induction heating.For example,heated at 1900 K for 60 min at 10-3 Pa,little residue Cu exist in the spongy Wdisc;and Cu formed a stalactiteon the condenser.The novel induction heating technique outperforms the conventional wet chemical method in many ways,including the environmental friendliness,much shorter time,higher purity.The surface segregation and vacuum evaporation of Cu from W-Cu alloy was theoretically analyzed.The calculated and measured results were in good agreement.

As the core component of space traveling wave tubes, the cathode-heater assembly is required to be stable, reliable, long life and low power consumption. In this paper, an estimation method of thermal contact resistance is proposed, and the thermal characteristics of cathode-heater assembly structure are simulated. Meanwhile, thermal experiment is designed and undertaken, and the whole temperature distribution of cathode-heater assembly structure under a variety of heating power is obtained for the first time. Furthermore, the thermal boundary and excitation of cathode-heater assembly structure is modified, and the values of thermal contact resistances are obtained by interactive method. Finally, a high reliable thermal model of cathode-heater assembly structure is obtained. It is revealed that cathode temperature calculating accuracy is within 5%, and the calculating error of whole structure is less than 72°C .

The interference fit of the three components of the slow wave structure of the space-borne helix trav-eling wave tube,including the clamping rods,tube housing and periodic permanent magnet unit,was mathematically modeled,theoretically analyzed,and numerically simulated in finite element method with software Inventor and AN-SYS.The impact of the mould displacement (extrusion)on the stress,strain,tube’s deformation,and buckling de-formation originated from random fabrication error,was investigated.The calculated and simulated results provide the security scope and success probability of the interference fit.In addition,dependence of the interference fit on the length and thickness of the tube housing was also simulated.The interference fit was found to strongly depend on the thickness,but weakly on the length of the tube;the thinner the tube,the weaker the yield strength,and the higher success probability.

The (Ba1-xSrx)La4Ti4O15 (x=0.8-0.95) ceramics were prepared by the solid-state reaction method and the phase compositions, crystal structures and microwave dielectric properties were investigated. The results show that the (Ba1-xSrx)La4Ti4O15 ceramics have the main phase of SrLa4Ti4O15 and the second phase of SrLa8Ti9O15. The SEM images indicate that the Ba0.2Sr0.8La4Ti4O15 ceramic with dense microstructures has grain sizes of about 10-20 mu m and clear crystal boundaries. The grain shapes of the (Ba1-xSrx)La4Ti4O15 ceramics change with increasing x values, and the pores in the samples increase. (Ba1-xSrx)La4Ti4O15 ceramics with x=0.8 possesses excellent microwave dielectric properties, listed as follows, the dielectric constant epsilon(r) = 40.86, the quality factor Qxf approximate to 62806 GHz, and the temperature coefficient of resonant frequency tau(f) = -20 X 10(-6)/degrees C. The monotone increases of the dielectric constant epsilon(r) and the quality factor Qxf of the ceramics with increasing Ba2+ contents, mean that the proper substitution of Ba2+ for Sr2+ can improve microwave dielectric properties of the (Ba1-xSrx)La4Ti4O15 ceramics.

研究了H3BO3或SiO2掺杂(质量分数为0.02％～2.00％)对0.61CaTiO3-0.39LaAlO3陶瓷的烧结温度、晶体结构及微波介电性能的影响.结果表明,微量的H3BO3或SiO2掺杂可使0.61CaTiO3-0.39LaAlO3陶瓷的烧结温度从1 380℃降至1 340℃,2.00％以内的H3BO3或SiO2掺杂不会改变陶瓷的物相组成.在H3BO3掺杂质量分数为2.00％时,样品的微观形貌发生了很大的改变,烧成的陶瓷稀疏多孔,密度急剧下降.研究表明,H3BO3或SiO2掺杂对0.61CaTiO3-0.39LaAlO3陶瓷的介电常数εr及谐振频率温度系数τf没有很大的影响,但降低了陶瓷的品质因数Q.当质量分数为0.02％时,H3BO3或SiO2掺杂后的0.61CaTiO3-0.39LaAlO3陶瓷的微波介电性能最佳:H3 BO3掺杂的陶瓷样品的εr=41.65,品质因数与频率之积Q×f=48 565 GHz,τf≈-1μ℃-1；SiO2掺杂的陶瓷样品的εr=41.48,Q×f=39 491 GHz,τf≈-1μ℃-1.

The microwave dielectric ceramics 0.65CaTiO3-0.35LaAlO3(CTLA) was prepared by solid state reaction technique.The crystal structure,sintering properties and microwave dielectric properties of the CTLA ceramics were investigated.The results showed that the CTLA ceramics only had the main phase of Ca0.65La0.35Al0.35Ti0.65O3 without a second phase.The CTLA ceramics sintered between 1 380~1 450 ℃ exhibited excellent microwave dielectric properties:er=44.5,τf≈0,Q×f≈43 948 GHz.The additives of 10% Nb2O5 increased densification sintering temperature to 1 300 ℃ but microwave properties was variant.er=38,τf=-2.8×10-6/°C and Q×f=13 260 GHz.

Microwave dielectric properties of (1−x)BaZn2Ti4O11–xBaNd2Ti4O12 (x=0–1.0) ceramics were investigated by the solid-state reaction with the purpose of finding a microwave ceramics with high dielectric constant (ɛr), high quality factor (Q×f) and low temperature coefficient of resonant frequency (τf). A two phase system BaZn2Ti4O11–BaNd2Ti4O12 was formed and SEM photographs show equiaxed BaZn2Ti4O11 grains and columnar BaNd2Ti4O12 grains. The microwave dielectric properties were strongly determined by the chemical composition. As increasing x from 0 to 1.0, the phase composition varied from pure BaZn2Ti4O11, to the two phase system BaZn2Ti4O11–BaNd2Ti4O12 and then to pure BaNd2Ti4O12. Therefore, the ɛr raised from 29.1 to 82.0 and the Q×f values decreased from 54,630GHz to 8110GHz, and the τf values increased from −29ppm/°C to 94ppm/°C. 0.8BaZn2Ti4O11–0.2BaNd2Ti4O12 ceramics sintered at 1250°C for 2.5h had ɛr=39.1, Q×f=37,850GHz and τf=−9ppm/°C.

Cordierite gel is synthesized by water-based sol-gel route, starting from basic magnesium carbonate and Al(NO(3))(3) inorganic solution dissolved in silica-ethanol sol. Crystallizing process of xerogels is confirmed by TG-DSC and X-ray diffraction. The mu-cordierite is formed firstly, then small amount of beta-SiO(2) and Mg-Al spinel are identified, at the same time the sapphirine is formed through the chemical reactions from beta-SiO(2). and Mg-Al spinel, and finally transformed to alpha-cordierite entirely. The obtained powders are analyzed by SEM and granularity analysis. The results show that more pure, fine and uniformly dispersed cordierite powders can be manufactured by water-based sol-gel method. The cordierite ceramics shown low dielectric constant (epsilon<5), low dielectric loss (tan delta<0.004) and low thermal expansion coefficient (alpha<1.85x10(-6)/degrees C).