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Title: Lifetime experimental study of graphite cathode for relativistic backward wave oscillator

Abstract

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.

Authors:
 [1];  [2]; ;  [3]
  1. Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)
  2. (China)
  3. Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)
Publication Date:
OSTI Identifier:
22597761
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 120; Journal Issue: 3; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Wu, Ping, Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024, Sun, Jun, and Chen, Changhua. Lifetime experimental study of graphite cathode for relativistic backward wave oscillator. United States: N. p., 2016. Web. doi:10.1063/1.4959133.
Wu, Ping, Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024, Sun, Jun, & Chen, Changhua. Lifetime experimental study of graphite cathode for relativistic backward wave oscillator. United States. doi:10.1063/1.4959133.
Wu, Ping, Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024, Sun, Jun, and Chen, Changhua. 2016. "Lifetime experimental study of graphite cathode for relativistic backward wave oscillator". United States. doi:10.1063/1.4959133.
@article{osti_22597761,
title = {Lifetime experimental study of graphite cathode for relativistic backward wave oscillator},
author = {Wu, Ping and Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 and Sun, Jun and Chen, Changhua},
abstractNote = {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.},
doi = {10.1063/1.4959133},
journal = {Journal of Applied Physics},
number = 3,
volume = 120,
place = {United States},
year = 2016,
month = 7
}
  • A compact P-band coaxial relativistic backward wave oscillator with three periods slow wave structure was investigated experimentally. The experimental results show that the frequency of the P-band coaxial relativistic backward wave oscillator is 897 MHz and the microwave power is 1.47 GW with an efficiency of about 32% in the case in which the diode voltage is 572 kV, the beam current is 8.0 kA, and the guide magnetic field is about 0.86 T. In addition, the device can generate a 3.14 GW microwave radiation as the guide magnetic field increases to 1.2 T at the diode voltage of 997more » kV and the beam current of 15.3 kA. The experimental results are in good agreement with those obtained earlier by numerical simulations.« less
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