An axial monotron with rippled wall resonator

Summary form only given. Consisting of an electron beam that traverses a standing-wave cavity resonator, the monotron ranks as the simplest microwave tube. The effect of the beam on the cavity fields can be described in terms of the functional dependence of the dynamic beam conductance upon the transit time of the election through the resonator Negative values of the conductance represent work done by the beam on the fields so that the beam acts as a source, that can be used for self-excitation or regenerative amplification of electromagnetic oscillations in the cavity. Besides its simplicity and compactness, recent studies have indicated that the monotron operating in an azimuthally symmetric TM mode can reach 20.0 percent conversion efficiency at weakly relativistic beam energies, unlike past predictions of a maximal theoretical efficiency of 14.5 percent. Devoted to exploring novel concepts of monotron resonant structures, the present work proposes a sinusoidally rippled wall cavity which distinguishes itself by providing efficient coupling to a coaxial output circuit. The synthesis of the cavity relics on the properties of periodic guiding structures from which we formulate the dispersion relation for waveguides with sinusoidally rippled wall. On the basis of 2.5-D particle-in-cell (PIC) simulation, we discuss the operation of the corrugated-cavity monotron thus envisaged to operate at 10.5 GHz with coaxial loading. Then using a centered, solid beam at the injection parameters of 50A current and 34keV input energy, the simulation gives the average power output of 260kW, which amounts to 15.3 percent overall efficiency. The conclusions of the paper are presented in the last part, which reviews the monotron design by highlighting its attributes.