Power coupling to helicon and Trivelpiece-Gould modes in helicon sources

G. G. Borg; R. W. Boswell

doi:10.1063/1.872748

Power coupling to helicon and Trivelpiece-Gould modes in helicon sources

G. G. Borg^*, R. W. Boswell

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

56 Citations (Scopus)

Abstract

The effects of finite electron mass on the helicon mode and the role of the Trivelpiece-Gould (TG) mode in helicon sources are considered. In an unbounded plasma these waves are commonly referred to as whistler waves. A simple cold plasma antenna-wave coupling code gives results which compare favorably with experimental observations of the whistler wave resonance cone. The connection between these cones and the Trivelpiece-Gould eigenmodes of bounded plasmas is discussed. The theory is applied to the study of antenna-wave coupling in helicon sources. It reveals that finite electron mass effects do not significantly improve antenna-wave coupling for ω/ω_ce <0.5. It is also suggested that, because of the resonance cone dispersion, eigenmode cavity resonances of the Trivelpiece-Gould mode could be difficult to excite in practice. This precludes geometric resonances of the antenna impedance due to the existence of the TG mode as an explanation for the high plasma production efficiency of helicon sources.

Original language	English
Pages (from-to)	564-571
Number of pages	8
Journal	Physics of Plasmas
Volume	5
Issue number	3
DOIs	https://doi.org/10.1063/1.872748
Publication status	Published - Mar 1998

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title = "Power coupling to helicon and Trivelpiece-Gould modes in helicon sources",

abstract = "The effects of finite electron mass on the helicon mode and the role of the Trivelpiece-Gould (TG) mode in helicon sources are considered. In an unbounded plasma these waves are commonly referred to as whistler waves. A simple cold plasma antenna-wave coupling code gives results which compare favorably with experimental observations of the whistler wave resonance cone. The connection between these cones and the Trivelpiece-Gould eigenmodes of bounded plasmas is discussed. The theory is applied to the study of antenna-wave coupling in helicon sources. It reveals that finite electron mass effects do not significantly improve antenna-wave coupling for ω/ωce <0.5. It is also suggested that, because of the resonance cone dispersion, eigenmode cavity resonances of the Trivelpiece-Gould mode could be difficult to excite in practice. This precludes geometric resonances of the antenna impedance due to the existence of the TG mode as an explanation for the high plasma production efficiency of helicon sources.",

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AU - Borg, G. G.

AU - Boswell, R. W.

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N2 - The effects of finite electron mass on the helicon mode and the role of the Trivelpiece-Gould (TG) mode in helicon sources are considered. In an unbounded plasma these waves are commonly referred to as whistler waves. A simple cold plasma antenna-wave coupling code gives results which compare favorably with experimental observations of the whistler wave resonance cone. The connection between these cones and the Trivelpiece-Gould eigenmodes of bounded plasmas is discussed. The theory is applied to the study of antenna-wave coupling in helicon sources. It reveals that finite electron mass effects do not significantly improve antenna-wave coupling for ω/ωce <0.5. It is also suggested that, because of the resonance cone dispersion, eigenmode cavity resonances of the Trivelpiece-Gould mode could be difficult to excite in practice. This precludes geometric resonances of the antenna impedance due to the existence of the TG mode as an explanation for the high plasma production efficiency of helicon sources.

AB - The effects of finite electron mass on the helicon mode and the role of the Trivelpiece-Gould (TG) mode in helicon sources are considered. In an unbounded plasma these waves are commonly referred to as whistler waves. A simple cold plasma antenna-wave coupling code gives results which compare favorably with experimental observations of the whistler wave resonance cone. The connection between these cones and the Trivelpiece-Gould eigenmodes of bounded plasmas is discussed. The theory is applied to the study of antenna-wave coupling in helicon sources. It reveals that finite electron mass effects do not significantly improve antenna-wave coupling for ω/ωce <0.5. It is also suggested that, because of the resonance cone dispersion, eigenmode cavity resonances of the Trivelpiece-Gould mode could be difficult to excite in practice. This precludes geometric resonances of the antenna impedance due to the existence of the TG mode as an explanation for the high plasma production efficiency of helicon sources.

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ER -

Power coupling to helicon and Trivelpiece-Gould modes in helicon sources

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