Hydromagnetic surface waves along a compressible cylindrical plasma column surrounded by neutral gas

Abstract

The characteristics of hydromagnetic surface waves propagating along the interface of a compressible cylindrical plasma column surrounded by neutral gas embedded in a steady magnetic field along the axis of the cylinder are studied by varying the ratio of the magnetic field and the relative density of the two media. Symmetric and asymmetric modes are found to exist. When Alfven speed 'v A ' is less than the sound speed 's' in the neutral gas the symmetric mode suffers lower cutoff in k for propagation. The cutoff window is narrowed when the magnetic field in the neutral gas is increased. For v A > s, the density of the neutral gas is found to suppress, restrict to a certain window, and allow the free propagation of both modes. There exists a critical magnetic field ratio for certain environments, in which both slow and fast surface waves are present simultaneously in symmetric and asymmetric modes. The findings for a special case are found to be in agreement with those obtained for an isolated magnetic flux tube studied earlier.

Dispersion relation of azimuthal electromagnetic surface waves on a magnetized plasma column in a dielectric lined slow-wave waveguide

“…The parameters of such discharges depend on many factors, such as type of electromagnetic surface waves used [3]. In this case, the study of surface waves and their excitation by an electron beam on the cylindrical surfaces of a magnetized plasma column has become important [12][13][14][15][16][17]. It is well-known that surface waves are qualitatively a type of electromagnetic oscillations of a bounded medium that on the plasma-vacuum interface are often E-type with field components E z , E x , B y if the interface of two media is the yz plane [18,19].…”

Excitation of electromagnetic surface waves by an annular electron beam in a plasma waveguide with a dielectric rod and a magnetized plasma column

“…Therefore, in an axial magnetized plasma waveguide the propagation of surface waves along the symmetry axis can produce a long plasma layer. In this case, the study of surface waves and their excitation by an electron beam on the cylindrical surfaces of a magnetized plasma column has become important [18,19,[28][29][30][31][32][33]. It is well known that TWTs and backward-wave oscillators (BWOs) usually include an intense electron beam as their active medium [20,[34][35][36][37].…”