Dispersion characteristics of the dipolar modes in a wave guide partially filled with a magnetoplasma column

The electromagnetic wave propagation in a partially filled plasma wave guide is studied by using both the quasistatic and the exact analyses. The cutoff and resonant frequencies are examined analytically to predict all possible modes, and numerical methods are then used to study the complete dispersion characteristics. Because of the geometrical generality of the problem, the fully filled plasma wave guide and the plasma column in free space can be considered as special cases. The classifications of the modes existing in various regions are clarified. The effect of the ratio of the plasma and wave guide radii and the d.c. axial magnetic field on the modes is observed and discussed. With a close study of cutoffs, it is shown that the 'special unpaired mode,' named by Bevc, can now be paired with another mode in the gyroresonance region. For large values of the propagation constant, asymptotic dispersion equations can be derived and turn out to be the same in both analyses. Comparisons between the two sets of results are also made to examine the validity of the quasistatic analysis.