An evaluation of different antenna designs for helicon wave excitation in a cylindrical plasma source

Abstract

Articles you may be interested inA segmented multi-loop antenna for selective excitation of azimuthal mode number in a helicon plasma source Rev. Sci. Instrum. 85, 093509 (2014); 10.1063/1.4896041 Towards an optimal antenna for helicon waves excitation J. Appl. Phys. 98, 083304 (2005); 10.1063/1.2081107Measurements and code comparison of wave dispersion and antenna radiation resistance for helicon waves in a high density cylindrical plasma source A magnetohydrodynamic numerical model, based on the finite element method, is employed to analyze the antenna radiation resistance in a cylindrical helicon wave driven plasma source. The antenna radiation resistances of four commonly used antennas are compared. The effects on antenna radiation resistance of frequency, plasma density, density profile and the system dimensions are investigated. It is confirmed that mϭϩ1 is the most strongly excited mode. It is shown that the plasma density gradient tends to suppress the excitation of negative m-modes. Some wave field patterns are also presented which demonstrate commonly observed features in the experiments such as the beat patterns of copropagating radial modes. The findings highlight the importance of antenna radiation resistance modelling as a first step to a self consistent model of the discharge physics of cool dense helicon wave driven sources.

Generalized theory of helicon waves. II. Excitation and absorption

“…(14) for V i = J i , for example, it is now possible to make some general comments about the effects of neglecting TG waves by setting E z = 0 and including only the Hall terms 2,4 D (i.e., m e = 0) or the Hall and transverse field diagonal terms 5 S in the dielectric tensor (i.e., m e finite but P → ∞). This will facilitate the comparison of our results with those of previous authors 2,5,9 . The general expression is …”

Helicon wave excitation with rotating antenna fields

“…However, more complete calculations [13,16] that include antenna coupling, plasma inhomogeneity, and damping indicate strong differences in the excitation of m = +1 and -1 modes. For the helical antennas used here and typical experimental plasma profiles and parameters, the plasma loading for the m = +1 mode is predicted to be 2.7 Ω, compared with 0.26 Ω for m = -1, in rough agreement with our observations.…”

Wave propagation and absorption simulations for helicon sources

“…Their model includes temperature effects in the plasma dielectric tensor, which are necessary to model Landau damping. Kamenski and Borg 10 developed a one-dimensional magnetohydrodynamic numerical model, which is based on a finite-element method to analyze helicon wave coupling and the antenna radiation resistance for various antennas in a cylindrical, axially uniform, cold plasma. In a later paper, 11 they developed a one-dimensional cylindrical kinetic wave code, which includes the effects of collisional dissipation and Landau damping that are necessary for the description of wave absorption.…”

“…Several one-dimensional models that assume radially nonuniform plasma density and temperature profiles and axially uniform applied magnetic field and plasma density, have been presented in the literature. [9][10][11][12][13] Fischer et al 9 examined helicon wave coupling and power absorption in a finite plasma column, assuming an axially uniform plasma and applied magnetic field. Their model includes temperature effects in the plasma dielectric tensor, which are necessary to model Landau damping.…”