Propagation of azimuthal waves in magnetoactive waveguides filled with a current-carrying plasma

It is shown that a cylindrical metallic waveguide fully filled with a magnetoactive plasma can propagate coupled ordinarily polarized bulk and extraordinarily polarized surface waves along its azimuthal direction. Interaction between these waves is studied in the case when an external magnetic field has axial and azimuthal components. For the case of a regular profile, a practically convenient analytical expression for a correction to the eigenfrequency of the waves that is due to the external azimuthal magnetic field is derived.