Evaluating the Performance of a Carbon-Epoxy Capillary Cathode and Carbon Fiber Cathode in a Sealed-Tube Vircator under UHV Conditions

Evan Rocha, Patrick M. Kelly, Jonathan M. Parson, Curtis F. Lynn, James C. Dickens, Andreas A. Neuber, John J. Mankowski, Tal Queller, Joseph Gleizer, Yakov E. Krasik.

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

This paper evaluates the performance of a bimodal carbon fiber cathode and a carbon-epoxy multicapillary cathode operating within a reflex-triode sealed-tube virtual cathode oscillator (vircator). The experimental results reveal that both cathodes exhibit similar emission behavior, although with some significant operational differences. An eight-stage 84-J pulse-forming network-based Marx generator serves to drive both cathodes at 250 kV and 3-4 kA with a ∼ 70 -ns pulsewidth. Both cathodes undergo conditioning over 10 000 pulses to determine gas evolution as well as electrical changes over time. Gas evolution of both cathodes is observed using a residual gas analyzer to determine individual gas constituents. A comparison of diode voltage, diode current, RF output, and outgassing data for both cathodes during vircator operation over 10 000 pulses is presented to quantify cathode performance in a sealed-tube vircator. Changes in cathode surface morphology, from virgin to postmortem, are discussed. Data for various anode-cathode gap distances, from 3 to 15 mm, are presented. The evolution of voltage and current inputs to the vircator is discussed.

Original languageEnglish
Article number7163638
Pages (from-to)2670-2675
Number of pages6
JournalIEEE Transactions on Plasma Science
Volume43
Issue number8
DOIs
StatePublished - Aug 1 2015

Keywords

  • Cathodes
  • electron emission
  • electron tubes
  • high power microwave generator.

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