粒度调控对钡-钨阴极表面发射微区的影响  

Influence of Particle Size Control on Surface Emission Micro-Area of Barium-Tungsten Cathode

作　　者：何学良 周增林 李艳[1] 陈文帅 惠志林 He Xueliang;Zhou Zenglin;Li Yan;Chen Wenshuai;Hui Zhilin(GRIMAT Engineering Institute Co.,Ltd,Beijing 101407,China;State Key Laboratory of Advanced Materials for Smart Sensing,GRINM Group Co.,Ltd,Beijing 100088,China;General Research Institute for Nonferrous Metals,Beijing 100088,China)

机构地区：[1]有研工程技术研究院有限公司,北京101407 [2]有研科技集团有限公司智能传感功能材料国家重点实验室,北京100088 [3]北京有色金属研究总院,北京100088

出　　处：《稀有金属材料与工程》2022年第1期280-285,共6页Rare Metal Materials and Engineering

基　　金：国家重点研发计划专项(2017YFB0306000)。

摘　　要：为了在微米尺度探究未分级钨粉、分级钨粉制备的钨基体在阴极热电子发射性能上的差异,深入了解阴极表面微区电子发射过程和阴极发射机理,采用新型深紫外激光发射电子显微镜/热发射电子显微镜系统(DUV-PEEM/TEEM)对2种钨粉制备的阴极表面进行了光电子、热电子成像分析。结果显示,与未分级钨粉相比,分级钨粉制备的钨基体的显微组织更加均匀,且闭孔率由1.44%降至0.47%;光电子+热电子联合成像精确得出2种阴极的发射均主要集中于孔隙及孔隙中的活性物质上;通过热电子图像对比及分析表明,分级钨粉制备的阴极的热电子发射微区面积更大、分布更均匀;且在1050℃工作条件下,分级钨粉制备的阴极的脉冲电流密度为30.79 A/cm^(2),发射斜率为1.38;综合分析显示,其具备更理想的本征热电子发射能力和发射均匀性。In order to research the cathodic thermionic emission performance difference of tungsten matrix prepared by ungraded tungsten powder and graded tungsten powder on the micron scale, and to gain a deeper understanding of the electron emission process of the cathode surface micro-area and the cathode emission mechanism, a newly developed instrument aiming at meeting the special operation requirements of thermal dispenser cathode was used. This instrument called DUV-PEEM/TEEM combines the functions of deep ultraviolet laser photo-emission electron microscope and thermal-emission electron microscope. Thanks to the powerful functions of DUV-PEEM/TEEM, the photoelectron and thermoelectron images of surface of the cathode prepared by two kinds of tungsten powders were analyzed. The results show that compared with the ungraded tungsten powder, the microstructure of the tungsten matrix prepared by the graded tungsten powder is more uniform, and the closed porosity reduces from 1.44% to 0.47%. The photoelectron and thermionic united imaging accurately shows that the emission of the two cathodes mainly locates at the pores and active substances of pores. Via the comparison and analysis of thermal electron(TEEM) images, the thermal electron emission micro-area area of the cathode prepared by graded tungsten powder is larger and the distribution is more uniform than those of the cathode prepared by ungraded tungsten powder. Under the working condition of 1050 ℃, the pulse current density of the cathode prepared by graded tungsten powder is 30.79 A/cm^(2), and the emission slope is 1.38. The comprehensive analysis shows that the cathode prepared by grade tungsten powder has more ideal intrinsic thermionic emission capability and emission uniformity.

关 键 词：热阴极 深紫外激光 光发射电子显微镜 热发射电子显微镜 电子发射 

分 类 号：O462.1[理学—电子物理学] TN104.1[理学—物理]