一种新型高发射性能扩散阴极的实现与验证
发布时间：2018-12-31 20:18
【摘要】：随着新型太赫兹器件的迅速发展,阴极的发射性能需要达到40-100A/cm2。这一性能指标几乎已达到传统覆膜浸渍扩散阴极的性能极限。在现有的各种阴极类型中,含钪扩散阴极具有很高的发射水平,是最有可能达到新型太赫兹器件要求的阴极。本文研制了一种新型浸渍扩散阴极,所用浸渍活性物质的特点是,在铝酸盐活性物质的基础上首次同时引入Sr0和Sc203；新阴极的电子发射性能达到了172A/cm2。此外,本文还对阴极的蒸发速率及寿命进行了测试,并对阴极表面作了纳米扫描俄歇扫描分析。获得的主要结论如下： 1.对阴极基体—钨海绵体进行了研究。一开始我们采用粒径30-60nm的钨粉来制备钨海绵体,但发现,采用模压或等静压成型后,进行高温浸渍得到的浸渍度明显偏低(4%左右)；将钨粉和发射物质按重量比混合压制成型之后再高温烧结,很难获得成形良好的发射体；最后我们采用3-4pm的分级钨粉和传统制备工艺,获得了孔度为20%-25%、孔隙分布均匀的钨海绵体,采用这一钨海绵体浸渍铝酸盐,可获得6.5-7.2%的浸渍度,可较好地满足阴极对活性物质浸渍度的要求。 2.设计了新的活性物质(Ba-Sr-Sc-Al-Ca-O)成分系统。在传统铝酸盐基础上,首次同时引入SrO和Sc2O3。实验表明,优化SrO和Sc203比例可使阴极获得优异的电子发射能力。采用26BaO·29SrO·8Sc203·7CaO·Al203配方的新型活性物质浸渍的阴极,在1100℃,脉冲发射电流密度达到172A/cm2,远高于传统M型阴极的发射电流密度。实验还测量了阴极的欠热曲线和功函数,测量及分析结果表明,新阴极具有良好的电子发射均匀性。 3.利用纳米扫描俄歇显微镜等表面分析手段对新阴极表面原子层成分分布进行了分析。结果显示,新阴极表面均匀覆盖了高浓度的Ba、Sc和O的原子层,Ba：Sc元素之比与文献中获得最佳发射的成分比例相一致。 4.研制了满足太赫兹器件要求的微型带状注阴极。带状注阴极设计要求：尺寸为1mmx0.3mm,发射性能达到50A/cm2。我们采用在圆端面上构造小矩形的方法来制备微型带状注阴极。矩形以外的部分覆盖钼硅化合物薄膜以抑制电子发射。将阴极装入太赫兹器件进行了发射测试,在300μs,20Hz的工作条件下,阴极工作温度为1080℃,实测发射电流密度达到了80A/Cm2。
[Abstract]:With the rapid development of new terahertz devices, the emission performance of the cathode needs to reach 40-100A / cm ~ 2. This performance index has almost reached the performance limit of the traditional coated impregnated diffusion cathode. Among the existing cathodes, the Scandium-containing diffusion cathode has a high emission level and is the most likely cathode to meet the requirements of new terahertz devices. A new impregnated diffusion cathode has been developed in this paper. The characteristic of the impregnated active material is that the electron emission properties of the new cathode Sr0 and Sc203; are 172A / cm ~ 2 for the first time on the basis of aluminate active material. In addition, the evaporation rate and lifetime of the cathode were measured, and the surface of the cathode was analyzed by nano-scanning Auger scanning. The main conclusions are as follows: 1. The cathodic matrix tungsten cavernous was studied. At first, we used tungsten powder with particle size of 30-60nm to prepare tungsten sponge, but it was found that the impregnation degree of high temperature impregnation was obviously lower (about 4%) after molding or isostatic pressing. It is difficult to obtain a well-formed emitter when tungsten powder and emitter are mixed and pressed according to weight ratio and then sintered at high temperature. Finally, by using the 3-4pm graded tungsten powder and the traditional preparation process, the tungsten sponge with a porosity of 20-25 and a uniform pore distribution is obtained. By impregnating the aluminate with this tungsten sponge, the impregnation degree of 6.5-7.2% can be obtained. It can meet the requirements of the cathodic impregnation degree of active substances. 2. A new active substance (Ba-Sr-Sc-Al-Ca-O) composition system was designed. On the basis of traditional aluminate, SrO and Sc2O3. are introduced simultaneously for the first time. The experiments show that the cathode can obtain excellent electron emission ability by optimizing the ratio of SrO and Sc203. At 1100 鈩，
本文编号：2397065
[Abstract]:With the rapid development of new terahertz devices, the emission performance of the cathode needs to reach 40-100A / cm ~ 2. This performance index has almost reached the performance limit of the traditional coated impregnated diffusion cathode. Among the existing cathodes, the Scandium-containing diffusion cathode has a high emission level and is the most likely cathode to meet the requirements of new terahertz devices. A new impregnated diffusion cathode has been developed in this paper. The characteristic of the impregnated active material is that the electron emission properties of the new cathode Sr0 and Sc203; are 172A / cm ~ 2 for the first time on the basis of aluminate active material. In addition, the evaporation rate and lifetime of the cathode were measured, and the surface of the cathode was analyzed by nano-scanning Auger scanning. The main conclusions are as follows: 1. The cathodic matrix tungsten cavernous was studied. At first, we used tungsten powder with particle size of 30-60nm to prepare tungsten sponge, but it was found that the impregnation degree of high temperature impregnation was obviously lower (about 4%) after molding or isostatic pressing. It is difficult to obtain a well-formed emitter when tungsten powder and emitter are mixed and pressed according to weight ratio and then sintered at high temperature. Finally, by using the 3-4pm graded tungsten powder and the traditional preparation process, the tungsten sponge with a porosity of 20-25 and a uniform pore distribution is obtained. By impregnating the aluminate with this tungsten sponge, the impregnation degree of 6.5-7.2% can be obtained. It can meet the requirements of the cathodic impregnation degree of active substances. 2. A new active substance (Ba-Sr-Sc-Al-Ca-O) composition system was designed. On the basis of traditional aluminate, SrO and Sc2O3. are introduced simultaneously for the first time. The experiments show that the cathode can obtain excellent electron emission ability by optimizing the ratio of SrO and Sc203. At 1100 鈩，
本文编号：2397065
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