Open AccessOn small‐signal amplification of a TM circular cylindrical wave‐guide mode in a gyro‐TWT
Author(s) -
Kalyanasundaram Natarajan,
Saini Jasmine
Publication year - 2013
Publication title -
iet microwaves, antennas and propagation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.555
H-Index - 69
eISSN - 1751-8733
pISSN - 1751-8725
DOI - 10.1049/iet-map.2012.0571
Subject(s) - physics , radius , gyrotron , cyclotron , traveling wave tube , amplifier , optics , beam (structure) , signal (programming language) , phase velocity , phase (matter) , electron , computational physics , computer security , optoelectronics , cmos , quantum mechanics , computer science , programming language
A self‐consistent kinetic‐theory based method of analysing the small‐signal amplification of a transverse magnetic (TM) mode of a circular cylindrical waveguide linearly interacting with an annular beam of gyrating electrons in a gyro‐travelling wave tube (TWT) configuration is presented. When the cyclotron‐resonance condition is enforced over the entire frequency range by allowing the gyro‐radius and the relativistic factor to be frequency‐dependent for a constant value of the axial electron speed chosen to coincide with the reciprocal of the TM‐mode phase speed at a particular frequency, the initial growth rate of the interacting TM wave is seen to exhibits a shallow minimum close to, but shifted to the right of, that frequency. The growth‐rate curve, however, exhibits two maxima on either side of the minimum, a sharp but large maximum to the left and a broad but a smaller maximum to the right. A gyro‐TWT designed by choosing the amplifier parameters (none of them varying any longer with frequency) in such a way as to place the broad maximum of the growth‐rate curve at the design frequency is shown to be capable of operation over a wide band of frequencies around the design frequency coupled with a decent value of small‐signal gain and negligible frequency distortion.