HIGHER RADIAL MODES OF AZIMUTHAL SURFACE WAVES IN CYLINDRICAL WAVEGUIDES WITHOUT EXTERNAL MAGNETIC FIELD

The properties of higher order radial modes of electromagnetic azimuthal surface-type waves (ASW) which propagate in partially plasma-filled cylindrical waveguides without external magnetic field are analyzed using analytical and numerical techniques. For a waveguide with plasma surrounded by dielectric material and encased in metal, the eigenfrequencies for higher order radial modes are obtained. It is found that the ASW higher radial modes propagate with shorter vacuum wavelength than the zeroth order radial modes and that the more favourable conditions for higher order radial mode propagation are for ASW’s with larger azimuthal wavenumber in waveguides with wider dielectric layer and larger dielectric constant. A further salient feature of ASW higher radial modes is that a change in plasma waveguide parameters causes a drastic change in ASW eigenfrequency in contrast to the zero-th order modes which have a smoother frequency variation with effective wavenumber.