Resonant effect of the noncircular shape of the plasma surface on the dispersion properties of extraordinary azimuthal surface modes in magnetoactive waveguides

Influence of the shape of the cross section of a plasma-dielectric interface on the dispersion properties of high-frequency azimuthal surface modes

“…However, in a waveguide in which the plasma-dielectric has a noncircular cross section, ASWs with certain azimuthal mode numbers, namely, |m| = N/2, are generally nondegenerate [21]. Let us remind for comparison, that even in a weak ( ӷ ε 0 ) magnetic field, ceteris paribus, the dis persion properties of LF ASWs with these azimuthal mode numbers (|m| = N/2) are more sensitive to the shape of the cross section of the plasma-dielectric interface than those of LF ASWs with other azimuthal mode numbers (|m| ≠ N/2) [22]. The reason is that, for LF ASWs with azimuthal mode numbers such that And vice versa: if m < 0 then the denominator D (+) is small (in this case it is expressed by Eq.…”

Influence of the Plasma Column Cross-Section Non-Circularity on the Excitation of the Azimuthal Surface Waves in Electron Cyclotron Frequency Range by Annular Electron Beam

“…It is well known from the theory of wave propagation in media with periodical properties along some direction [24] that the amplitudes of the satellite harmonics are small values (the order of (h N ) j ) in comparison with the amplitude of the fundamental harmonic. A wave packet which consisted of the fundamental and the two nearest satellite (j = 1) harmonics with fields which are proportional to exp[i(m ± N )ϕ − iω t] has been considered in [18,19] to study the dependence of the ASW dispersion properties on the shape of the noncircular cross section of the plasma-vacuum interface. Such an approach is based on the fact that taking into consideration the higher satellite harmonics gives a contribution to the eigen ASW frequency correction which is of the third and higher orders of the small parameter of the problem h N .…”

“…It was shown in [19] that the largest effect of the plasma-vacuum interface curvature on the dispersion properties of the LF ASW is caused in the resonant case N = 2|m|, when the angular period of the wave perturbations is equal to just two periods of the inhomogeneity of the plasma-vacuum interface. This resonance is caused by the fact that The same as in Figure 4, but for m = +3 and m = −3.…”

“…It was shown in [19] that the resonant effect of the noncircular cross section of the plasma column on the ASW dispersion properties is larger for larger values of the parameter N . That is why in this paper we studied the influence of the value N on the ASW growth rate while keeping the resonant condition N = 2|m|.…”

“…It was shown that in this case the frequency spectrum and the spectrum composition of the wave packet are predetermined by the shape of the plasma column cross section. Additionally, the effect that the plasma cross section shape has on the LF ASW dispersion properties has been investigated in the case when the angular period of the wave perturbation is exactly twice the inhomogeneity period of the plasma-dielectric interface [19].…”