亚微米结构新型含钪扩散阴极性能的研究

Characteristics of Scandate-Type Cathode with Sub-Micron Structure Sc_2O_3 Doped Tungsten Bodies

本文研究具有氧化钪掺杂钨基体钪酸盐阴极的性能。为了改进氧化钪的分布均匀性及提高阴极表面钪的扩散补充能力,分别采用液固掺杂和液液掺杂的方法制备了Sc2O3掺杂W粉基材,研究了利用这种钨粉制作多孔钨基体的工艺技术和多孔体的微观结构。研究表明在改进压制、烧结技术的基础上,可以获得具有适当孔度的亚微米结构多孔基体,氧化钪在基体中的分布得到进一步改善,在这种基体中铝酸盐的浸渍率可以达到常规浸渍阴极的要求。发射试验结果表明,这种阴极在850℃的工作温度下空间电荷限制的电流密度超过30A/cm2,在超过2000h的寿命实验过程中发射仍持续上升,因而在要求高电流密度和一定寿命的微波电子管中具有光明的应用前景。研究还证实多孔体的结构越趋细微,越有利于阴极的发射均匀性和耐离子轰击的性能改善。

Characteristics of Scandate cathodes with Scandia doped tungsten bodies have been investigated in this work. To improve the distribution uniformity of Sc2O3 and the supplement of Sc to the surface of the cathodes, technologies have been studied to manufacture sub-micron structure porous bodies with uniformly distributed Sc2O3 and the cathodes with these bodies. The Scandia doped tungsten powders were made by both liquid-solid doping method and liquid-liquid doping method on the basis of previous researches. The study shows that on the basis of improving pressing and sintering process, we can obtain sub-micron porous bodies with proper porosities. The content of impregnated Ba,Ca aluminates in the bodies can meet the requirements of the conventional impregnated cathode. Emission experiment results show that the space charge limited current density of this kind of cathode has reached more than 30 A/cm^2 at 850 . The study also illustrates that the finer structure of porous bodies will be beneficial for improving the cathode emission uniformity and resistance to ion bombardment.