Multi-resonance interaction in rectangular waveguide grating structure

Abstract

For developing millimeter and sub-millimeter wave devices, the rectangular waveguide grating sheet beam system is a very promising way to realize a high power operation. To further improve the interaction efficiency, we can substitute the cyclotron beam for the rectilinear one and utilize the multi-resonance effect. In rectangular coordinates, we rigorously derive the formulae to describe the Lorentz forces acting on the electrons and the coupling coefficients of each concerned resonance. The theoretical calculation demonstrates that the combined gain is evidently enhanced when the multi-resonance condition is satisfied, the occurrence of which is always caused by the coupling of two major resonances. The results also show that the multi-resonance effect will rapidly disappear if the beam voltage and the magnetic field deviate from their exact values. Although the parameters should be carefully sustained, the multi-resonance can be excited by using the fundamental TEx10 hybrid mode, which is beneficial for the stable operation. So, as an available mechanism to upgrade the future device performance, it is worth being particularly studied.