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15 - Magnetrons

Published online by Cambridge University Press:  27 April 2018

Richard G. Carter
Richard G. Carter
Affiliation:
Lancaster University
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Summary

In a magnetron oscillator electrons emitted from a cylindrical cathode interact with the π-mode resonance of a cylindrical, re-entrant, slow-wave structure on the anode. The electrons move under the influence of a radial static electric field and an axial magnetic field. Rotating spokes of charge synchronous with the wave on the anode are formed on the surface of a space-charge hub. As the electrons drift outwards along the spokes the change in potential energy is converted to r.f. energy with high efficiency. Because a magnetron is an oscillator its steady-state operation is always non-linear. Care must be taken in the design of the anode and in the operation of the tube to avoid excitation of modes other than the π-mode. The design of the anode is considered in detail. The performance of magnetrons is reviewed including the effects of the external match on frequency, power output and efficiency. Useful understanding of the properties of a magnetron can be gained from a model which assumes a fixed hub, determined by the theory of the cut-off magnetron diode, and rigid spokes. This model reproduces all the main features of the performance of a magnetron.

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Microwave and RF Vacuum Electronic Power Sources , pp. 565 - 628
Publisher: Cambridge University Press
Print publication year: 2018

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  • Magnetrons
  • Richard G. Carter, Lancaster University
  • Book: Microwave and RF Vacuum Electronic Power Sources
  • Online publication: 27 April 2018
  • Chapter DOI: https://doi.org/10.1017/9780511979231.016
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  • Magnetrons
  • Richard G. Carter, Lancaster University
  • Book: Microwave and RF Vacuum Electronic Power Sources
  • Online publication: 27 April 2018
  • Chapter DOI: https://doi.org/10.1017/9780511979231.016
Available formats
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Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Magnetrons
  • Richard G. Carter, Lancaster University
  • Book: Microwave and RF Vacuum Electronic Power Sources
  • Online publication: 27 April 2018
  • Chapter DOI: https://doi.org/10.1017/9780511979231.016
Available formats
×