Study on Morphology and Chemical States of Surface Active Layer of Th-W Cathode
Abstract
:1. Introduction
2. Experiment Methods
3. Results and Discussion
3.1. Original Microstructure of Wire
3.2. The Morphology and Structure of the Surface Active Layer
3.3. Study on the Valence State of Surface-Active Layer
4. Conclusions
- Under the action of vacuum and high temperature, the tungsten matrix recrystallises, the grain boundaries increase and the active atoms migrate outwards along the grain boundaries, which facilitates the formation of the active layer.
- For surfaces where an active layer has formed, the etching action of the Ar+ lance removes the active layer from the surface of the tungsten substrate. After the surface oxides and active elements have been removed, the surface is at this point almost composed of tungsten and such a surface does not have good electron emission capability.
- The active layer formed by the thorium-oxygen compound at high temperature would produce metal ultrafine particles, which increase the concentration of high-energy valence electrons, reduce the electron work function, and improve the emission capability.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Element | Test Position | Cross-Sectional | Average Value | Longitudinal Section | Average Value |
---|---|---|---|---|---|
Th | 1 | 30.76 | 31.87 | 26.21 | 24.35 |
32 | 23.8 | ||||
33.35 | 23.04 | ||||
2 | 15.91 | 16.82 | 4.63 | 5.21 | |
17.1 | 6.1 | ||||
18.17 | 4.9 | ||||
W | 1 | 54.15 | 53.26 | 45.47 | 46.26 |
53.8 | 47.1 | ||||
52.33 | 46.21 | ||||
2 | 76.13 | 75.31 | 60.06 | 59.66 | |
75.2 | 58.7 | ||||
74.6 | 60.22 | ||||
O | 1 | 17.09 | 14.87 | 28.32 | 29.39 |
15.2 | 29.1 | ||||
13.32 | 30.75 | ||||
2 | 9.79 | 7.87 | 35.3 | 35.13 | |
7.7 | 35.2 | ||||
6.12 | 34.89 |
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Cheng, Y.; Sun, Y.; Zhou, Y.; Wang, S.; Meng, J.; Cao, N.; Shi, W. Study on Morphology and Chemical States of Surface Active Layer of Th-W Cathode. Materials 2022, 15, 2726. https://doi.org/10.3390/ma15082726
Cheng Y, Sun Y, Zhou Y, Wang S, Meng J, Cao N, Shi W. Study on Morphology and Chemical States of Surface Active Layer of Th-W Cathode. Materials. 2022; 15(8):2726. https://doi.org/10.3390/ma15082726
Chicago/Turabian StyleCheng, Yin, Yuan Sun, Yizhou Zhou, Shiyang Wang, Jie Meng, Nan Cao, and Wanpeng Shi. 2022. "Study on Morphology and Chemical States of Surface Active Layer of Th-W Cathode" Materials 15, no. 8: 2726. https://doi.org/10.3390/ma15082726