Frequency tuning a reflex triode vircator from 1.5 to 5.9 GHz

Curtis F. Lynn, Jonathan Parson, Patrick Kelly, Mark Taylor, David Barnett, Andreas Neuber, James Dickens, John Mankowski, Steve Calico, Michael Scott

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

4 Scopus citations

Abstract

Vircators (virtual cathode oscillators) are easily frequency tunable by simply altering the electron beam current density through either adjusting the accelerating voltage or varying the anode cathode gap (A-K gap). It is noted that vircators typically exhibit frequency hopping, an often undesired feature. Here we address the frequency hopping problem by introducing a rectangular shaped carbon fiber cathode with the width of the cathode less than one quarter of a wavelength in the direction of microwave propagation. Operating the vircator with the rectangular cathode revealed a match with a resonant condition from back wall reflections, which explains the observed dominant microwave frequency selection. That is, the vircator emitted stably during 50 ns operation at 3.89 GHz or 2.07 GHz with a 3 dB bandwidth of 37.5 MHz or 93.7 MHz, at A-K gap spacing of 8 mm, and 12 mm respectively. To further investigate frequency tuning, the A-K gap was swept from 3 mm to 17 mm while keeping a constant 5.1 cm diameter circular cathode. The resulting frequencies of operation were 1.5 GHz, 2.1 GHz, 4.1 GHz, 4.6 GHz, and 5.9 GHz at A-K gap spacing of 17mm, 14 mm, 7 mm, 5.75 mm, and 3 mm respectively. This demonstrates that a tuning range of 4.4 GHz should be achievable for a practical vircator system.

Original languageEnglish
Title of host publicationProceedings of the 2014 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2014
EditorsAllen L. Garner
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages209-212
Number of pages4
ISBN (Electronic)9781467373234
DOIs
StatePublished - Oct 1 2015
EventIEEE International Power Modulator and High Voltage Conference, IPMHVC 2014 - Santa Fe, United States
Duration: Jun 1 2014Jun 5 2014

Publication series

NameProceedings of the 2014 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2014

Conference

ConferenceIEEE International Power Modulator and High Voltage Conference, IPMHVC 2014
Country/TerritoryUnited States
CitySanta Fe
Period06/1/1406/5/14

Keywords

  • High power microwaves
  • cold cathodes
  • electron beams

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