The dispersion properties of flute electromagnetic waves propagating across an external axial static magnetic field in traveling-wave-tube-like waveguides with low-density plasma filling are investigated. The cylindrical structure consists of a central dielectric rod, placed inside a plasma coaxial layer with a metallic helix sheath on its outer interface, and a metal screen separated from the helix by another dielectric layer.
Azimuthal surface waves are eigenmodes of cylindrical plasma–dielectric–metal structures both in the presence of and without an axial static magnetic field. They are actively studied due to possible applications in plasma electronics, nanotechnologies and biomedical diagnostics. Higher radial modes are known to propagate at higher frequencies and shorter wavelengths compared to those of the zeroth mode, a feature which is of interest for practical applications. To gain the advantage of the excitation of higher radial modes of azimuthal surface waves one has first to know their dispersion properties. This paper generalizes the results of earlier papers by including a static axial magnetic field and considering the higher radial modes. The presence of the constant axial magnetic field removes the degeneracy in the wave spectrum with respect to the sign of the azimuthal wavenumber.
AZIMUTHAL SURFACE WAVES IN LOW-DENSITY PLASMA LOADED, COAXIAL HELIX TRAVELING-WAVE-TUBE-LIKE WAVEGUIDES
