Microstructure Characterization of Graphite Cathodes for Explosive Field-Emission

Abstract:

Explosive field-emission graphite has the advantages of low cost, long lifetime, low outgassing rate and can operate stably at a large number of pulses, thus it has become an important candidate for repetition frequency, long-pulse high-power microwave (HPM) devices. In this paper, two types of graphite cathodes with different microstructures are investigated on their explosive field-emission properties. These cathodes are operated in a vacuum diode system at a voltage of 230 kV and a pulse duration of ~110 ns. The study reveals that the graphite cathode with smaller, cross-linked grains generates higher current at shorter current risetime compared to the cathode with larger grains. Furthermore, the microstructure defect regions of the graphite cathodes are more susceptible to destruction than the perfect microcrystalline regions during explosive emission process due to the combination effects of explosion of surface microprotrusions and Joule heating.

• Periodical: Applied Mechanics and Materials (Volume 248)
• Pages: 268-273
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.248.268
• Online since: December 2012
• Authors: Jun Bing Chuan, Hong Wan, Jie Yang, Fan Zhou
• Keywords: Emission Properties, Graphite Cathode, Microstructure

References

[1] Baker R J, Scham iloglu E. High-power microwave sources and technologies. Tusinghua University Press, Beijing(2004).

[2] Liu G Z. Physics of field-induced explosive emitting cathode. Test and Research, 27, 1(2004).

[3] Zhong Wenli. The study of cathode materials used in the field of high power microwave. National University of Defense technology, (2008).

[4] Jin Zhenxing, Zhang Jun, et al. Preliminary experimental investigation on repetitively long pulse HPM generation using graphite cathode. High Power Laser and Particle Beams, 23, 1307(2011).

DOI: 10.3788/hplpb20112305.1307

[5] G. Bekefi, F. Hartemann, D. A. Kirkpatrick. Temporal evolution of beam emittance from a field emission electron gun. J. Appl. Phys. 62, 1564 (1987).

DOI: 10.1063/1.339634

[6] M. Inagahi, M. Shiraishi, et al. The Evaluation of Graphitization Degree. Carbon, 5, 39(1991).

[7] Liu Guozhi, Sun Jun, Shao Hao, et al. Experimental study on effective emitting area of explosive emitting cathode. High Power Laser and Particle Beams. 17, 249(2005).

[8] S.D. Korovin, E.A. Litvinov, G.A. Mesyats et al. Experimental Investigation of Graphite Explosive-Emission Cathode Operating in a Periodic Pulse Regime. Technical physics Letters, 30, 813(2004).

DOI: 10.1134/1.1813718

[9] G. Compagnini, O. Puglisi and G. Foti. Raman Spectra of Virgin and Damaged Graphite Edge Planes. Carbon, 35, 1973(1997).

DOI: 10.1016/s0008-6223(97)00141-3

[10] Noda Tokichi, Various raw materials of carbon - Heating treatment of lattice constant change. Journal of chemical industry, 1961, 1370-1375.

[11] Guo Jinling, et al. By using Scherrer formula to calculate the grain size should be pay attention to several issues. Journal of Inner Mongolia Normal University (Natural Science Edition), 3, 357(1995).