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Study of Noise in Crossed-Field Devices.

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Final technical rept. 15 Apr 77-30 Sep 79,

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This research effort addresses the fundamentals of noise in electron beams in crossed field microwave tubes. Recent evolvement of new applications for DOD requires tubes with better noise characteristics in addition to the higher bandwidth and gain characteristics of crossed field devices. Much work was expended in this type of research up to 1969 but thereafter concepts have remained neglected and unexplored until 1977 when efforts were renewed. The approach here is to re-examine the analyses using simple models, to resolve various unknowns and gaps in knowledge and to investigate original unexplored avenues with which we can gain more insight into the mechanisms of fluctuation and modulation in electron beams travelling in crossed electric and magnetic fields. In the first years effort, expressions were derived based on kinetic theory for the seven moments over the energy distribution function in a plasma thermionic diode with crossed electric and magnetic fields, both for the space-charge limited and magnetic-field limited situations. The expressions are given as integrals over the distribution function at the cathode surface, whose form is left arbitrary. Analytic results, valid in the region of the potential minimum, are provided in the space-charge limit when the potential profile is assumed to be parabolic in the vicinity of its minimum. The seven moments are the density profile, the two current flux components, the two mean velocity components and the two mean square velocity components.

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  • Electrical and Electronic Equipment

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