Asymmetric modes suppression in Cerenkov device using anisotropic media

Abstract

Asymmetric modes competition in Cerenkov devices were studied with a view to developing a novel method to suppress modes competition, based on loading of the slow-wave structure (SWS) with an anisotropic medium. Due to differences in the field distribution between the asymmetric and symmetric modes, the asymmetric modes are susceptible to significant attenuation in anisotropic media with an appropriate imaginary part for the azimuthal permittivity. In contrast, the symmetric modes, such as the TM01 mode, incur no such losses. Using the EH11 mode as an example, the quality factor obtained from experiments involving the SWS loaded with an anisotropic medium was reduced by approximately 90% compared with that for a copper SWS. The attenuation was sufficiently high that the electromagnetic fields for the asymmetric modes were barely established, indicating that the suppression technique was highly effective. The approach provides a feasible way to eliminate asymmetric modes in high-power microwave (HPM) sources and may lead to a range of new applications in HPM systems.