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介绍了两种阴极,即稀土钼金属陶瓷次级发射材料及钪钨基扩散阴极。研究结果表明,稀土钼金属陶瓷阴极的最大次级发射系数可达6.5,与单元稀土氧化物掺杂的钼阴极相比,复合稀土氧化物-钼具有更高的次级发射系数,主要是由于复合氧化物在高温、真空条件下失氧速度小于单元稀土氧化物,相对于单元稀土氧化物具有较低的缺陷浓度,使缺陷对二次电子的散射作用减弱,从而有利于阴极的发射。钪钨基扩散阴极具有优异的热发射性能,900℃下阴极的发射电流密度达87A/cm~2,为普通钪酸盐阴极的3倍。活性元素Ba、Sc和O在阴极激活过程中同时向表面扩散,在阴极表面建立均匀分布的Ba、Sc和O活性层,促进了阴极的发射。 相似文献
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用溶胶.凝胶(Sol-Gel)法制备了RE(RE=La,Y)-Mo复合氧化物粉末,工艺条件:初始溶液pH值=1,于550℃分解胶体,500℃,900℃ 2次还原粉末。采用XRD,TEM对还原后粉末的相组成、形貌、粒度进行分析。结果表明:500℃还原后,单质Mo衍射峰出现,RE以非晶态RE-O-Mo存在;900℃2次还原后,RE以氧化物形式存在。红外光谱(FT-IR)分析结果表明,La和Y通过O与Mo键合,削弱Mo=O键,使稀土钼复合氧化物可还原性增强。TEM分析表明,还原后稀土钼粉末粒径在70nm左右。 相似文献
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A Study on La_2O_3-Y_2O_3-Mo Secondary Emission Material 总被引:1,自引:0,他引:1
Thephenomena ,mechanismandtheapplicationofsecondaryemissionofmanykindsofmaterialshavebeenstudiedsincethesecondaryemissionphenomenawasdiscoveredbyCompellin 1899.Withthedevel opmentofelectronictechnologythephenomenaofsec ondaryemissionhavebeenincreasinglyappliedinmanyfields[1,2 ] ,especiallyinhighpowermagnetrontube .Nowadays ,thecathodesofhighpowermag netrontubeusedinthefieldsofbroadcast,correspon denceandnationaldefensearemainlyBa Wcath odes[3] andsomeTh Wcathodes .However ,Ba Wcathodeishard… 相似文献
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采用液相共沉淀法制备了612铝酸盐(n(BaO):n(CaO):n(Al2O3)=6:1:2)前驱粉末, 在不同气氛(H2、CO2、N2)、不同温度(1300℃、1400℃、1500℃)焙烧制备铝酸盐, 系统研究了不同工艺制备的铝酸盐对钡钨阴极性能的影响。结果表明: 前驱粉末的最佳焙烧工艺为: H2气氛、1500℃, 可获得主相为Ba5CaAl4O12的铝酸盐, 用其制备的钡钨阴极发射电流密度可达12.2 A/cm2, 蒸发速率仅为1.09×10-8 g/(cm2?s)。 相似文献
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Scandia and rhenium doped tungsten powders were prepared by solid-liquid doping combined with two-step reduction method. The particle size of doped tungsten and distribution of scandia and rhenium were studied by SEM, EDS, XRD and granularity analysis. Experimental results showed that scandia distributed evenly on the surface of tungsten particles. Addition of scandia and rhenium decreased the particle size of doped tungsten, and the more the content of scandia and rhenium, the smaller the doped tungsten particles. Tungsten powders doped with 3 % Sc2O3 and 3 % Re (mass fraction) had an average size of about 80 nm in diameter. The mechanism of the decrease in the tungsten particle size was discussed. 相似文献
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La2O3 and Y2O3 co-doped Mo secondary emitters were prepared by three kinds of doping method combined with high temperature plasma sintering.The secondary electron emission property and microstructure of the cathodes were studied.It showed that the cathode prepared by liquid-liquid doping method exhibited the best emission property among all the samples prepared by liquid-solid doping,solid-solid doping and liquid-liquid doping methods due to a uniform distribution of different substances.RE2O3 existed unifo... 相似文献
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碳化La2O3—Mo阴极材料的高温XPS研究 总被引:6,自引:0,他引:6
采用高温X射线光电子能谱(XPS)对碳化La2O3-Mo阴极材料表面La的价成进行了研究。结果表明,材料中的La2O3可以被Mo2C还原成单质La。单质La的结合能高于La2O3的结合能。从实验上证实单质La3d5/2的结合能为835.96eV,并首次给出单质La3d3/2结合能实验数值为852.23eV。 相似文献