Dynamic cyclotron resonance in relativistic microwave devices with linear electron beams

Abstract

Summary form only given. There are experimental works of different authors where are reported the dependence of output radiation power versus magnitude of focusing magnetic field. In present work we analyze theoretically and by numerical simulation dependencies of output radiation versus magnitude of focusing magnetic field when the magnetic field magnitude is sufficiently smaller than the value corresponding to cyclotron absorption. High power microwave devices based on interaction of high-current relativistic electron beam guided by strong enough homogeneous magnetic field with synchronous electromagnetic field of periodically corrugated waveguide. The high frequency electromagnetic field amplitude is high for optimum regimes with high efficiency level. In this case some electrons are accelerated and different electrons are decelerated during interaction inside the device. As a result, cyclotron resonance conditions are different for different electron groups. We have found theoretically conditions of dynamic cyclotron resonance when it is possible to improve efficiency of interaction in devices with distributed interaction such as TWT, BWO, generator of diffractional radiation by combination of Cherenkov and cyclotron interactions in strong nonlinear regimes with optimum efficiency levels. The numerical simulation of interaction between initially linear electron beam and electromagnetic field has shown that there are regions of efficiency improvement up to 50 and amplitude of high-frequency electromagnetic field. One of the important feature of such combined interaction is dependence on relativistic factor. We have found optimum region of relativistic factors by numerical simulation. The results of numerical simulation were compared with experimental data referring to relativistic diffractional generators and multiwave Cherenkov generators. Good agreement in value of optimum magnitude of guiding magnetic field was obtained.