High-efficiency wideband gyro-TWTs and gyro-BWOs with helically corrugated waveguides

Bratman, V.L. and Denisov, G.G. and Samsonov, S.V. and Cross, A.W. and Phelps, A.D.R. and Xe, W. (2007) High-efficiency wideband gyro-TWTs and gyro-BWOs with helically corrugated waveguides. Radiophysics and Quantum Electronics, 50 (2). pp. 95-107. ISSN 0033-8443 (https://doi.org/10.1007/s11141-007-0009-9)

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Abstract

We review the studies of gyrotron-type microwave devices whose electrodynamic system has the form of an oversized metal waveguide with a helically corrugated internal surface. For certain parameters, such a corrugation changes radically the waveguide dispersion ensuring an almost constant group velocity of the eigenmode for a small (close to zero) longitudinal wave number in a wide frequency band. The use of ``helical'' waveguides along with electron optical systems which form near-axis electron beams makes it possible to create high-efficiency amplifiers based on gyro-traveling-wave tubes (gyro-TWTs) with a wide instantaneous frequency band of amplification and gyro-backward-wave oscillators (gyro-BWOs) with continuous wideband tuning of the oscillation frequency. The studied devices are superior to the well-studied microwave sources of this type (gyroklystrons and gyrotrons) in frequency band, by more than an order of magnitude, and are not inferior to them in efficiency even for a wide spread of electron velocities.