A boundary‐value problem treatment of an electric dipole in a warm isotropic plasma using the multiple water bag model

Abstract

A boundary‐value problem for a dipole immersed in a warm isotropic plasma has been solved using the multiple water bag (MWB) and fluid models of the plasma. The MWB model contains information on the electron distribution function, and hence gives results in agreement with the kinetic theory of the warm plasma. Comparing results from the MWB model with those from the fluid model, we find that the latter are correct only when the antenna frequency ω is sufficiently above the plasma frequency ωp. The current distribution and the driving‐point impedance are calculated for dipoles of several lengths. We find that the current distribution is triangular only when ω is well above ωp or when ω < ωl where ωl, is the frequency at which a resonance occurs in the driving point admittance; ωl is less than ωp and decreases with the increasing length of the dipole. The current distribution for frequencies close to ωp is oscillatory, with a complex wavenumber which is close to the wavenumber of the third‐order Landau mode. Only for very short dipoles with lengths less than 10 Debye lengths or so can the current distribution be approximated by a triangular one for all frequencies. The calculated frequency variation of the dipole resistance with frequency based on the MWB model is similar to those measured experimentally; for frequencies just below ωp the theory in this paper predicts a much larger resistance for the dipole than previous theories.

Plasma conditions in the polar ionosphere observed in SPW experiments of PPS system on board the Ohzora (EXOS-C) satellite.

“…Among these resonances the upper hybrid resonance always takes place as reflection of characteristics of the ambient plasma. The radiation resistance near upper hybrid resonance frequency and below that is calculated for the warm magnetized plasma including the effects of the electromagnetic radiation as well as the generation of the electrostatic plasma waves by SINGH (1978). The results show that the effective increase of the resistance near the upper hybrid frequency in the ionosphere usually takes place in a frequency range less than 10MHz, where the free space impedance of the antenna shows monotonic decrease.…”

A sleeve monopole antenna in a warm plasma

“…Figure 5 shows the current distributions of the sleeve antenna, taking Landau damping into account, for the sleeve of length 25 in. It is seen that the sinusoidal components decrease remarkably compared with the preceding case and their amplitude decrease gradually with the distance from the feed point [Singh, 1978]. Figure 9.…”

“…Substituting (8) into (7) and using the point-matching technique, we can evaluate the current distribution and the input impedance of the sleeve antenna. We find that a segment length of the order of Debye length (,lo = vol%) gives fairly accurate results [Singh, 1978].…”

Loaded two‐element ring antenna for electron plasma waves

“…This is It is a problem to determine the segmentation length of the antenna. We find that an order of Debye length (At) = Vo/Wp) brings fairly accurate results [Singh, 1978]. In this paper the linearized hydrodynamic theory is used, and so Landau damping does not appear explicitly.…”