Microwave Gas Discharge Sustained by the Azimuthal Surface Waves

Abstract

A theoretical model of plasma source based on azimuthal surface waves (ASW) propagation in a plasma filled cylindrical metal waveguide is presented. The ASW propagate across an external axial steady magnetic field and posses the eigenfrequencies in the range between upper hybrid frequency and the cut‐off frequency for HF bulk wave. The problem is studied using a local hydrodynamic approach and taking into consideration a collisional wave damping. Spatial distributions of the ASW fields and produced plasma density are examined both analytically and numerically.

Dispersion relation for azimuthal electromagnetic surface waves on a magnetized annular plasma in a metal waveguide with coaxial anisotropic dielectric inner coating

“…As shown in Figs 11(a) and 11(b) the number of spectrum solutions for ω pe = 3 × 10 10 Hz with decreasing electron cyclotron frequency is also decreasing, in contrast with the isotropic case. On the other hand, the number of spectra for ω pe = 3×10 11 Hz, ε ⊥d = 2ε d = 5.25, R a = 1 cm, R d = 3 cm and R c = 4 cm is similar to the isotropic case, i.e. by decreasing Ω e the number of frequency spectra is increased, as seen previously.…”

“…Hereê i is a unit vector in cylindrical coordinates and m is an integer. By substituting (10) and (11) into (1) and (2) the system of equations describing the general behavior of electric and magnetic fields in this geometry is obtained [14,19]. The field components E z and B z are strongly coupled with each other as follows:…”

“…It is obvious that the problem of electron-beam-plasma interactions is simplest if the plasma is placed inside a cylindrical metal waveguide with smooth walls [8,9]. On the other hand, the great interest in the problem of gas discharges sustained on surface waves is caused by their application in coating by plasma-enhanced chemical vapour deposition and/or etching for microelectronics [10][11][12]. The field of the surface wave is negligible deep in the plasma [13].…”

“…Graph of ω/ω pe versus the dielectric permittivity constant of the coaxial anisotropic dielectric, ε ⊥d , given by (25) for α = R b /R a = 1.1, R d = 3 cm and R c = 4 cm: (a) ω pe = Ω e = 1×1011 Hz; (b) ω pe = 1×1011 Hz, Ω e = 3×10 10 Hz; (c) • for ω pe = 3×1010 Hz, Ω e = 1 × 10 11 Hz and • for ω pe = Ω e = 3 × 10 10 Hz. Graph of the dispersion relation given by (25) for the dominant modes (m = ±1) versus α (the ratio of the internal to external radius of the annular plasma, R b /R a ) for ε ⊥d = 5.25, R a = 1 cm, R d = 3 cm and R c = 4 cm: (a) • for ω pe = Ω e = 1 × 10 11 Hz and × for both ω pe = Ω e = 1 × 10 11 Hz, 3 × 10 10 Hz; (b) • for ω pe = 3 × 10 10 Hz, Ω e = 1 × 10 11 Hz and • for ω pe = 1 × 10 11 Hz, Ω e = 3 × 10 10 Hz.…”

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

“…It is obvious that the problem of electron beam-plasma interaction is simplest if a plasma is placed inside a cylindrical metal waveguide with smooth walls and the plasma column is uniform over its length and azimuth [5][6][7][8]. On the other hand, the great interest in the problem of gas discharges sustained on the surface waves is caused by their application in coating by plasma-enhanced chemical vapour deposition and/or etching for microelectronics [9][10][11]. The parameters of such discharges depend on many factors, such as type of electromagnetic surface waves used [3].…”