Lifetime experimental study of graphite cathode for relativistic backward wave oscillator

Journal Article · Thu Jul 21 04:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4959133· OSTI ID:22597761

Wu, Ping ^[1]; Sun, Jun; Chen, Changhua ^[2]

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1. Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)
2. Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

Graphite cathodes are widely used due to their good emission properties, especially their long lifetime. Some previous papers have researched their lifetime under certain conditions and uncovered some important phenomena. This paper is dedicated to research the lifetime of the graphite cathode under higher power. In the lifetime test, the voltage and current amplitudes are about 970 kV and 9.7 kA, respectively. The repetition rate is 20 Hz. An X-band relativistic backward wave oscillator is used to generate high power microwave by utilizing the electron beam energy. The experimental results demonstrate that the emission property of the graphite cathode remains quite stable during 10{sup 5} pulses, despite some slight deteriorations regarding the beam and microwave parameters. The macroscopic morphology change of the cathode blade due to material evaporation is observed by a laser microscope. The mass loss of the graphite cathode is about 60 μg/C. Meanwhile, the observation by a scanning electron microscope uncovers that the original numerous flaky micro-structures are totally replaced by a relatively smooth surface at the mid region of the cathode blade and a large number of new micro-protrusions at the blade edges during the lifetime test.

• OSTI ID: 22597761
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 3 Vol. 120; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CATHODES
ELECTRIC POTENTIAL
ELECTRON BEAMS
ELECTRON MICROSCOPES
EMISSION
EVAPORATION
GRAPHITE
LIFETIME
MASS TRANSFER
MICROSTRUCTURE
MICROWAVE RADIATION
MORPHOLOGY
OSCILLATORS
RELATIVISTIC RANGE
SCANNING ELECTRON MICROSCOPY