Cyclotron effects in relativistic backward-wave oscillators operating at low magnetic fields

Alexander N. Vlasov, Anton S. Ilyin, Yuval Carmel

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

A small-signal theory of a resonant relativistic backward-wave oscillator (BWO) operating at a very low-guiding magnetic field is developed. The theoretical approach is based on the successive iteration method of analytical solution of the exact three-dimensional (3-D) equations of electrons' motion. It was shown that cyclotron resonance effects in relativistic BWO (400 kV) operating at low-focusing magnetic field can lead to three different regimes of combined Cerenkov-cyclotron interaction: 1) cyclotron absorption due to cyclotron resonance between an electron beam and a fast spatial harmonic of forward electromagnetic wave; 2) complete compensation of cyclotron absorption under certain conditions; and 3) efficiency enhancement at low-focusing magnetic field. The theoretical results are compared with measurements of the output microwave power and frequency of the Maryland X-band BWO at very low magnetic field (0.8-4 kG). The measured dependence of the microwave output power on the strength of the guiding magnetic field is consistent with this model. The measured dip in the output power at around 2 kG can be explained as a cyclotron absorption by the forward wave. Design of a BWO operating at low magnetic field has definite advantages compared with a traditional BWO because it provides considerable reduction of volume, weight, and energy consumption of BWO.

Original languageEnglish
Pages (from-to)605-614
Number of pages10
JournalIEEE Transactions on Plasma Science
Volume26
Issue number3
DOIs
StatePublished - 1 Jan 1998
Externally publishedYes

Keywords

  • Combined cerenkov-cyclotron interaction
  • Lowfocusing magnetic field
  • Relativistic backward-wave oscillator

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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