Electromagnetic Field Properties of Axial Modes in a Finite Length X-Band Slow Wave Structure

抄録

The electromagnetic field properties of axisymmetric transverse magnetic (TM) modes in a specific slow wave structure (SWS) typically used in high power X-band backward wave oscillators are studied numerically. The dispersion relations, electric field distributions, and quality factors of the axial resonant modes are calculated. It is found that some of the axial modes can be switched from the volume modes to the surface ones by changing only the axial boundary of the SWS while the dispersion relations do not alter. This causes a drastic change in quality factors and can be of practical interest for controlling the coupling between beam and TM modes in high-power microwave devices. The calculated dispersion relations are verified experimentally for the TM₀₁ mode.