The open plasmaguide in extremes of magnetic field

Waveguiding properties of a homogeneous circular column of plasma imbedded in free space are examined in the two limits of zero and large axial magnetic field. The plasma is assumed to be cold and collisionless with ion motion neglected. The modes with azimuthal variation are included in the investigation, and dispersion curves are presented. For the zero field case the higher-order modes are found under certain conditions to exhibit backward-wave characteristics. For the case of large magnetic field, the occurrence of unique waveguiding features is discussed. The assumptions made are approximated by certain laboratory plasmas and hence the results may be of practical importance.