Gyrotron Travelling Wave Amplifier for high field Electron Paramagnetic Resonance

Project: Research

Project Details


Experimental results are presented of the first successful gyrotron backward wave oscillator (gyro-BWO) with continuous frequency tuning near low terahertz region. A helically corrugated interaction region (HCIR) was used to allow efficient interaction over a wide frequency band at the second harmonic of the electron cyclotron frequency without parasitic output. The gyro-BWO generated a maximum output power of 12 kW when driven by a 40 kV, 1.5 A, annular-shaped large-orbit electron beam and achieved a frequency tuning band of 88-102.5 GHz by adjusting the cavity magnetic field. The performance of the gyro-BWO is consistent with 3D particle-in-cell (PIC) numerical simulations.

Layman's description

The first successful operation was achieved of a high power gyro-BWO with a wide frequency tuning capability in the low terahertz frequency range. A novel helically corrugated interaction region and thermionic cusp electron gun were used in the gyro-BWO. Stable single mode output was achieved in a wide frequency tuning range of ~16% with a maximum power of 12 kW and an electronic efficiency of 20%.

Key findings

In this sub-terahertz gyro-BWO experiment stable output frequency and power were demonstrated due to single mode operation. A maximum output power of 12 kW which corresponds to a 20% interaction efficiency was achieved with a 1.5 A 40 kV large orbit electron beam. A wide frequency tuning range of 88-102.5 GHz was achieved by tuning the cavity magnetic field. Excellent agreement was shown between the simulations of the gyro-BWO using MAGIC and the measured results in the experiments. This method can, in principle, be extended to the higher terahertz range.


This work was given as keynote talks by 6th UK, Europe, China Millimeter Waves and THz Technology Workshop by the Program Committee, Rome, Italy 2013 and the 55th American Physical Society, Division of Plasma Physics Annual Meeting at the 2013 conference in Denver Colorado, USA.
Effective start/end date1/06/1330/11/16


  • EPSRC (Engineering and Physical Sciences Research Council): £411,720.00

Research Output

Characteristic measurements of a wideband gyro-TWA operating in W-band

He, W., Zhang, L., Donaldson, C. R., Ronald, K., Phelps, A. D. R., Cross, A. W. & Cain, P., 1 May 2019. 2 p.

Research output: Contribution to conferencePaper

Open Access
11 Downloads (Pure)

Amplification of frequency-swept signals in a W-band gyrotron travelling wave amplifier

Zhang, L., Donaldson, C. R., Cain, P., Cross, A. W. & He, W., 11 May 2018, (Accepted/In press) In : IEEE Electron Device Letters . p. 1-4 4 p.

Research output: Contribution to journalLetter

Open Access
  • 28 Downloads (Pure)

    Periodic GW level microwave pulses in X-band from a combination of a relativistic backward wave oscillator and a helical waveguide compressor

    Macinnes, P., Bratman, V. L., Zhang, L., Denisov, G. G., He, W., Kolganov, N. G., Mcstravick, M., Mishakin, S. V., Robertson, C. W., Samsonov, S. V., Whyte, C. G., Young, A. R., Ronald, K., Phelps, A. D. R. & Cross, A. W., 13 Feb 2018, 2017 IEEE 21st International Conference on Pulsed Power, PPC. Piscataway, N.J.: IEEE, 4 p. 8291306

    Research output: Chapter in Book/Report/Conference proceedingConference contribution book

    Open Access
  • 9 Downloads (Pure)


    Measurement of components of a W-band gyro-amplifier using VNA

    Zhang, L. (Creator), He, W. (Creator), Donaldson, C. (Creator), Garner, J. (Contributor) & MCELHINNEY, P. (Contributor), University of Strathclyde, 14 Mar 2017


    Components measurement data for project "Gyrotron TWA for High Field EPR and high field DNP"

    Zhang, L. (Creator), He, W. (Creator), Donaldson, C. (Creator), MCELHINNEY, P. (Contributor), Garner, J. (Contributor) & Cross, A. (Owner), University of Strathclyde, 14 Mar 2017