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

阴生毅; 吕昕平; 任峰; 卢志鹏; 王欣欣; 王宇; 邯娇; 张琪; 李阳

doi:10.11999/JEIT210087

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

doi: 10.11999/JEIT210087

阴生毅^1, ,,
吕昕平²,
任峰¹,
卢志鹏^{1, 2},
王欣欣¹,
王宇¹,
邯娇¹,
张琪¹,
李阳¹

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

基金项目: 国家重点研发计划(2018YFB1105200)

详细信息

作者简介:
阴生毅：男，1964年生，研究员，研究方向为大电流密度阴极及其发射机理

吕昕平：男，1997年生，硕士生，研究方向为液相合成法制取新型高活性电子发射材料

任峰：男，1992年生，助理研究员，研究方向为热电子发射材料及其制备

卢志鹏：男，1993年生，博士生，研究方向为大电流密度阴极技术及覆膜阴极技术

王欣欣：女，1986年生，中级工程师，研究方向为覆膜浸渍阴极

王宇：男，1981年生，工程师，研究方向为覆膜阴极制备工艺

邯娇：女，1986年生，中级工程师，研究方向为阴极热子制备工艺

张琪：男，1982年生，工程师，研究方向为热阴极精加工技术

李阳：男，1990年生，工程师，研究方向为热阴极制备技术

通讯作者:
阴生毅　ysy210@163.com

中图分类号: O462.1
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- 被引次数: 0
出版历程
- 收稿日期: 2021-01-21
- 修回日期: 2021-04-19
- 网络出版日期: 2021-05-07
- 刊出日期: 2021-10-18

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

1.
Key Laboratory of High Power Microwave Sources and Technologies, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China
2.
University of Chinese Academy of Sciences, Beijing 100049, China

Funds: National Key R&D Program of China (2018YFB1105200)

摘要

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/cm²和218.5 A/cm²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/cm²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。
- 浸渍扩散阴极 /
- 电子发射 /
- 液相合成法 /
- 冷冻干燥法
Abstract: 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/cm² under close-spaced diode configuration and 218.5 A/cm² 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/cm² after having worked for 2010 hours. Via Deep UltraViolet laser-Photo Emission and Thermal Emission Electron Microscopy (DUV-PEEM/TEEM) analyzation, the phenomenon ofthermionic 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.
- Impregnated dispenser cathode /
- Electron emission /
- Liquid phase synthesis /
- Freeze-drying method

HTML全文

图 1 装有新型活性阴极的电子枪的结构示意图

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图 2 用于阴极直流发射寿命测试的玻璃管壳

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图 3 不同Ba:Sc原子比的阴极的脉冲发射双对数特性曲线

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图 4 浸渍随机取样的新型活性物质的3只阴极的脉冲发射特性曲线

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图 5 电子枪阴极脉冲发射特性曲线与发射寿命曲线

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图 6 阴极的Miram曲线和PWFD曲线

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图 7 900 °C氢炉烧结后的活性物质的粉末XRD衍射谱线

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图 8 机械混合法制得活性物质的微观颗粒形貌

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图 9 冷冻干燥法制得活性物质的微观颗粒形貌

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图 10 670 °C下含钪612阴极的热电子发射与紫外光电子发射图像(视场直径100 μm)

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图 11 670 °C下新型活性阴极的热电子(TEEM)与紫外-光电子(UV-PEEM)发射图像(视场直径100 μm)

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图 12 阴极表面元素在高度方向分布的情况

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图 13 钪系阴极的“二叉树”模型与钡钨阴极表面原子层模型

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表 2 机械混合法与冷冻干燥法制得活性物质的元素分布情况(%)

方法	机械混合法				冷冻干燥法
位置	a		b		a		b
元素	wt	at	wt	at	wt	at	wt	at
OK	18.17	52.56	18.84	56.51	17.37	52.78	18.08	54.07
AlK	01.67	2.86	01.86	03.30	05.11	09.20	05.13	09.08
SrK	08.51	4.49	08.15	04.46	05.78	03.21	05.32	02.91
CaK	02.69	3.11	02.66	03.19	03.78	04.59	03.36	04.00
ScK	19.85	20.43	11.96	12.77	08.52	09.20	08.67	09.23
BaL	49.11	16.55	56.53	19.75	59.44	21.03	59.44	20.72

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表 1 计算阴极表面功函数分布情况

发射负载 (A/cm²)	320	160	80	40
功函数峰值(eV)	1.490	1.505	1.540	1.550
肖特基eΔφ/eV	0.103	0.077	0.059	0.044
零场eφ/eV	1.593	1.582	1.599	1.594
半峰宽度 (eV)	0.089	0.151	0.190	0.194

下载: 导出CSV

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