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本文利用相关检测技术,并对测试管结构作了改进,很好地抑制了热电子本底及空间电荷效应,构成一种测量热阴极在工作温度下次级电子发射性能的新方法。以浸渍钪酸盐阴极为样品,测得在低的轰击电子能量和电子流情况下次级电子发射系数占随温度指数上升;轰击电子能量或轰击电子流较大时,温度对没有很大的影响。研究表明高温下钪酸盐阴极存在电子轰击热发射增大效应,对此本文提出内建场模型加以解释。 相似文献
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冷阴极磁控管是一种性价比很高的可靠微波源,它具有瞬时启动、寿命长、可靠性高、系统容易实现小型化的优点。选用钯钡合金和难熔金属钽作为冷阴极材料,钽环作为一次发射体,由场致发射提供一次电子,钯钡合金为二次发射体,钯钡合金在一次电子的轰击下产生二次电子,两者提供磁控管阴阳极电流,实现磁控管正常振荡。从理论上详细分析了钽环厚度和钯钡合金温度对冷阴极启动特性的影响,基于理论分析结果,开展不同钽环厚度和阴极温度条件下磁控管工作性能研究,最终选用厚度为0.05 mm 的钽环作为冷阴极一次发射体,阴极工作温度在315~836 益之间,成功研制输出功率20 kW的Ka 波段冷阴极磁控管,冷启动稳定时间小于5 s,工作寿命超过500 h 相似文献
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A new kind of Ba-W dispenser cathode impregnated with barium ytterbate has been deve-loped.It has good properties;high coefficient of secondary emission,strong ability of resisting oxygenpoisoning,high thermionic emission current density and more uniform emission on the cathode surface.The cathode is suitable for using as an electron emitter for microwave tubes,especially magnetrons. 相似文献
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为了提高Y-Gd-Hf-O阴极耐电子轰击能力,该文通过高能球磨、压制和高温氢气烧结,制备了一种Sc2O3掺杂Y-Gd-Hf-O压制式直热式阴极。该阴极在1550 °C工作温度下,经过10 W电子连续轰击480 h后,发射电流密度下降至初始值的87.5%,表现出良好的耐电子轰击能力。阴极表面的微观形貌、成分组成分析表明,经压制后氢气气氛烧结,阴极表面呈陶瓷状结构形态,有利于提高阴极的耐电子轰击能力;经高温烧结、激活后表面形成了n型半导体Y2O3-x层,对改善阴极表面导电性、降低逸出功和提高热发射有促进作用。 相似文献
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用射频噪声法测出了低气压放电灯(荧光灯、紧凑型节能灯、紫外杀菌灯等)阴极的零场发射电流,进而研究了阴极温度和阴极零场发射之间的变化规律,最后,得到了一种比较简单、方便、实用的测试阴极发射特性的方法。 相似文献
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介绍了一种新型的纳米薄膜钪钨阴极,该阴极在1000℃(亮度温度)可以提供至少150A/cm^2的拐点电流密度。同时作者指出:含钪阴极的发射机制倾向于热电子发射机制还是“场助热电子发射”机制主要取决于阴极表面发射小岛的形成和维持。 相似文献
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A scanning electron probe is used to study the secondary emission properties of the im-pregnated barium scandate dispenser cathode, the influence of the activation on the secondary emis-sion property, the secondary emission image and the secondary emission distribution over the surfaceof the cathode. At optimal activation, δ_m=3.56 (E_(pm)=700eV). The activation has a larger effect onδ when the activation temperature is higher than 1100℃. The distribution over the surface of thecathode is non-uniform. The half-peak width of the distribution curve over the surface is 0.4. Theexperimental phenomena are discussed in relation to surface analysis of the cathode. The theoreticallyderived binomial distribution curves over the surface fit much better with the experimental results. 相似文献
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为了提高大功率磁控管的输出功率,延长其使用寿命,采用难熔稀土氧化钆和过渡金属氧化铪制备大功率磁控管用新型直热式稀土铪酸钆陶瓷阴极,并对该阴极的热发射特性和寿命特性等进行了测试,热发射测试结果显示该阴极在1300℃ br即可提供0.1A/cm2发射电流密度,1600℃ br下可提供超过1.93A/cm2的发射电流密度.寿命实验结果显示,该阴极在1500℃ br,直流负载为0.5A/cm2的条件下,寿命已经超过4000h.最后,利用X射线衍射仪、扫描电镜、能谱分析仪、氩离子深度刻蚀俄歇电镜等设备分别对该阴极活性物质的分子结构,阴极表面微观形貌、元素成分及含量等进行了分析.结果表明,高温烧结合成了单一的铪酸钆物相,烧结过程中当一种Gd3+价稀土氧化钆掺入Hf4+价的过渡金属氧化铪时,会发生离子置换固溶,为了保持铪酸钆晶格的电中性,晶格中就会产生一个氧空位.当阴极在激活、老练、热发射测试时,会加速氧空位的生成,产生的氧空位越多,阴极表面导电性就会越好,这间接降低了逸出功,从而提高了阴极的热发射能力. 相似文献
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The emission and surface characteristics of a dispenser cathode coated with Re arestudied.It is found that the dispenser cathode coated with Re has both higher current densityand more uniform distribution of emission than the S-type cathode.The Auger images of Bashow that the Ba distribution on the surface of the cathode coated with Re is more uniform thanthat on the surface of the S-type cathode.The analytical results by XPS and low energy AESshow that the Ba on the surface of the cathode coated with Re has stronger metallic propertythan that on the surface of the S type cathode. 相似文献
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《Electron Devices, IEEE Transactions on》1973,20(3):321-329
Cold cathode emission has been obtained from forward-biased silicon p-n junctions whose p-surfaces were activated to a state of negative electron affinity. In operation, electrons injected into the p-layer diffuse to the surface where they are emitted into vacuum. An Si:SiO2 structure has been developed to overcome the problems associated with current crowding, and with this structure, efficiencies (ratio of emitted current to bias current) as high as 10 percent have been observed. Emitted current densities as large as 225 A/cm2and currents as large as 7 mA have been drawn under pulsed conditions, while continuous current densities of 2 A/cm2and currents of tens of microamperes have been drawn for many hours. The electrical characteristics exhibited space-charge-limited and emission-limited regimes as well as Schottky effect. The silicon cold cathode has advantages in applications such as vidicons, where some aspects of performance are presently limited by the thermionic cathode, and where power consumption and heat generation must be minimized. 相似文献
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Zekun Zhou Yue Shi Peisheng Zhu Yingqian Ma Huiying Wang Xin Ming 《International Journal of Electronics》2013,100(4):519-530
Various emission instabilities in oxide cathodes are discussed and interpreted by means of a model of dynamic surface emission centres. According to this model, barium atoms adsorbed on BaO, SrO or CaO on the surface of both the coating and the base metal can form effective emission centres. As bulk conduction through the grains is poor, the number of emitted electrons is larger than the number of electrons injected from the base metal under the high-current condition. Hence some grains are charged up to a high potential across the coating. This uneven potential distribution on the grain surface leads to a repeated bombardment of the grain by porous conducting electrons, which may produce dissociation of the oxide, secondary electron emission and heating of the grain. Since these processes alter the surface composition, which is a dominant factor in thermionic emission, instability of thermionic emission results. In extreme cases this instability may lead to local sparking. 相似文献
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Experimental and theoretical studies were carried out on the electrical response of a forward biased n+-p silicon junction under photoexcitation with high-intensity 60-ns laser pulses at λ=10.6 μm. The observed strong bias-dependent electrical pulses are associated to changes in the junction forward current due to the carriers of the high energy tail within the photoexcited hot-electron distribution. A thermionic emission model of hot electrons over the junction barrier account for the experimental results. According to this model and the measured electrical response, the temperature of the carriers is nearly 100 K higher than the lattice temperature, which essentially remains constant at room temperature 相似文献
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碳纳米管场致发射结构的研究 总被引:3,自引:0,他引:3
碳纳米管以其特有的电学性质而成为一种优良的冷阴极材料。在场致发射器件中,真空度是决定发射稳定性的一个重要因素。如果碳纳米管阴极附近的真空度太低,将产生打火、气体电离、离子回轰阴极等问题,将导致阴极发射电流的迅速衰减。本文通过对基于碳纳米管冷阴极的二极管和三极管的场发射特性的实验,分挤了残余气体压强与外加电压、发射体工作时间的关系以及碳纳米管阵列的I-E曲线,利用这些结果可以优化碳纳米管场致发射结构的设计。 相似文献
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多孔硅(Porous Silicon,PS)平面阴极的场发射电子能量高、发散角小、对真空度不敏感、响应快,尤其适合用作场发射显示的电子源,基于PS阴极的无放电气体激发发光也为新型环保的高效平面光源技术带来了希望。本文介绍了PS阴极的电子发射原理及其研究进展,展望了其在显示技术、无放电气体激发发光技术、金属线沉积、电子束刻蚀以及其他领域的应用前景。 相似文献
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近年来热阴极特别是钪系阴极得到充分发展,有望成为高功率微波的电子源。提出一种基于热阴极的新型“面包圈”式电子枪模型,以此电子枪作为相对论返波管的环形电子束发射源。通过仿真软件CST PARTICLE STUDIO对模型进行仿真验证,所得电子枪发射电流为786 A,阴极发射电流密度为30 A/cm2,电子束密度为305 A/cm2,电子通过率为99.9%。最后对热阴极在高功率微波器件中的应用进行了初步探索。 相似文献