利用活性浸渍物质提高热阴极电流密度的实验研究和理论模型  

Experimental Study and Theoretical Model for Increasing the Current Density of Thermionic Cathodes through Active Impregnant Substance

作　　者：阴生毅 吕昕平 任峰 卢志鹏 王欣欣 王宇 邯娇 张琪 李阳 YIN Shengyi;LÜ Xinping;REN Feng;LU Zhipeng;WANG Xinxin;WANG Yu;HAN Jiao;ZHANG Qi;LI Yang(Key Laboratory of High Power Microwave Sources and Technologies,Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院空天信息创新研究院高功率微波源与技术重点实验室,北京100190 [2]中国科学院大学,北京100049

出　　处：《电子与信息学报》2021年第10期3058-3067,共10页Journal of Electronics & Information Technology

基　　金：国家重点研发计划(2018YFB1105200)。

摘　　要：通过发展新的活性物质成分系统及其制备方法以提升钪系阴极的电子发射性能,是当今热阴极特别是大电流密度阴极领域的研究重点。该文提出一种由多元金属氧化物构成的新型高活性浸渍物质,显著提升了钪在阴极中的添加比例,大幅提高了阴极的发射电流密度。将冷冻干燥法应用到该活性物质前驱体的制备过程中,有效解决了传统固相合成方法在机械式破碎、研磨和混合等工序中存在的不可控、不均匀等问题。采用了新的成分系统与新的制备方法制得活性物质的阴极,在真空二极管测试和电子枪测试中分别取得了超过500 A/cm^(2)和218.5 A/cm^(2)的脉冲发射电流密度。在二极管直流测试条件下,阴极的寿命测试进行了10500 h后仍未出现发射电流下降的现象;而在电子枪中的大工作比(5%)脉冲测试条件下,阴极在工作了2010 h后仍维持了超过50 A/cm^(2)的较大发射电流密度。借助深紫外—光/热发射电子显微镜(DUV-PEEM/TEEM)分析发现,相较传统的钪系阴极,新制备的大电流密度阴极表面的热电子发射位点数量增加,微区发射面积显著增大。最后,提出一种“二叉树”发射模型,以期阐释钪系阴极采用新活性物质后获得高发射特性的物理机制。Developing new active substance composition system and its preparation method to enhance scandate cathode’s emission property is a hotspot in the research field of thermionic cathode especially high-emission cathode.A novel highly active impregnant substance consisting of polymetallic oxide which apparently increases scandium’s appending proportion and greatly enhances cathode’s emission current density is put forward in this paper.Freeze-drying method is applied into preparation of the active substance’s precursor and effectively solves the problem of inhomogeneity and uncontrollability in the mechanical crushing,grinding and mixing procedures of conventional solid-phase synthesis routine.Cathode which adopted novel composition system and substance acquired by new preparation routine reaches a pulse emission current density of above 500 A/cm^(2) under close-spaced diode configuration and 218.5 A/cm^(2) in an electron gun.Under the DC diode experimental configuration,the cathodes’emission lifetime test has endured for 10500 hours with no emission current drop;while in the electron gun with a pulse drive of heavy duty cycle(5%),the cathode maintains a big workload of more than 50 A/cm^(2) after having worked for 2010 hours.Via Deep UltraViolet laser-Photo Emission and Thermal Emission Electron Microscopy(DUV-PEEM/TEEM)analyzation,the phenomenon of thermionic emission points’amount increases and emitting micro-area expands on the newly prepared high-emission cathode’s surface is observed.Finally,a‘binary tree’emission model is brought up,hoping to explain the physical mechanism of scandate cathode’s high emission character with new active substance.

关 键 词：浸渍扩散阴极 电子发射 液相合成法 冷冻干燥法 

分 类 号：O462.1[理学—电子物理学]