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Carbon nanotube (CNT) cold-cathodes hold much promise in a variety of millimeter-wave and terahertz vacuum electronic radiation devices due to their inherent near instantaneous temporal turn-on and near-ideal ideal field electron emission performance. Here we report on the development of a CNT cold-cathode Ka -band backward-wave oscillator (BWO). Using a novel beam compression stage, theoretical studies, simulation results, and empirical findings collectively demonstrate that this device affords an unprecedentedly high output power of 230 W at a technologically important operating frequency of 33.65 GHz. The developed magnetic injection electron gun achieves a high emission current of 265.5 mA (emission current density of 188.3 mA/cm 2 ) and a high focused beam current density of 18.5 A/cm 2 , which our studies suggest, is essential to the BWOs high output power.
Original languageEnglish
Article number9388792
Pages (from-to)2467 - 2472
Number of pages6
JournalIEEE Transactions on Electron Devices
Issue number5
Early online date29 Mar 2021
Publication statusPublished - 31 May 2021


  • Backward wave oscillator (BWO)
  • carbon nanotube (CNT)
  • cold cathode
  • field emission (FE)
  • high power
  • millimeter-wave (MMW) radiation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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