Cross-field tubes

  • B. Epsztein
Part of the Microwave Technology Series book series (MRFT)


In cross-field tubes — also called ‘M-type’ tubes after magnetrons — the electron beam moves under the influence of perpendicular static electric and magnetic fields. As a result, its drift motion is perpendicular to both fields, while its average drift velocity depends only on the ratio of the absolute value of these fields. Such a beam is made to interact with a space harmonic of the electromagnetic wave propagating along a slow-wave structure. Since the drift velocity of the beam is constant, the beam does not give up its kinetic energy to the wave, as in the case of linear beam tubes — ‘O-type’ tubes (as opposed to M-type) such as klystrons, TWTs, etc. — but, instead, its potential energy, so that it remains synchronous with the wave while interacting with it. For this reason, high efficiencies are obtained.


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  2. Fisk, J. B., Hagstrum H.D. and Hartman P. L. (1946) The magnetron as a generator of centimeter waves. Bell System Tech. Journ. 25 167.CrossRefGoogle Scholar
  3. Gilmour A. S. (1986) Microwave Tubes, Artech House Dedham, Massachusetts, USA.Google Scholar
  4. Okress E. (1961) Crossed-Field Microwave Devices, Academic Press, New York.Google Scholar

Copyright information

© Bradford L. Smith and Michel-Henri Carpentier 1993

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  • B. Epsztein

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