Plasma production in a toroidal heliac by helicon waves

Loewenhardt, Peter; Blackwell, Boyd; Boswell, Rod; Conway, G. D.; Hamberger, S.M.

doi:10.1103/physrevlett.67.2792

Cited by 94 publications

(62 citation statements)

References 12 publications

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“…The reason for the high ionization efficiency of helicon discharges is not yet definitively known, though collisionless mechanisms, such as Landau and cyclotron damping, have been suggested by Chen [3] and Harvey and Lashmore-Davies [4], respectively. Helicon discharges have been suggested for semiconductor processing by Perry et al [5], Nakano et al [6], and Chen [7]; for gas laser excitation by Zhu and Boswell et al [8]; for plasma accelerators by Chen [9]; and for plasma injection into toroidal confinement devices by Leowenhardt et al [10].…”

Section: Introductionmentioning

confidence: 99%

Helicon wave excitation with helical antennas

1995

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Components of the wave magnetic field in a helicon discharge have been measured with a single-turn, coaxial magnetic probe. Left- and right-handed helical antennas, as well as plane-polarized antennas, were used; and the results were compared with the field patterns computed for a nonuniform plasma. The results show that the right-hand circularly polarized mode is preferentially excited with all antennas, even those designed to excite the left-hand mode. For right-hand excitation, the radial amplitude profiles are in excellent agreement with computations.

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Section: Introductionmentioning

confidence: 99%

Helicon wave excitation with helical antennas

1995

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“…They have been subsequently used for a variety of applications [2][3][4][5][6] . Radial amplitude profiles of helicon waves in uniform and nonuniform plasmas have been studied extensively by Chen et al [7][8][9] Azimuthal mode content in a high aspect ratio helicon discharge was investigated by Light and Chen,10 who found that the m = +1 (right-hand polarized) mode was preferentially excited in a variety of antenna and static magnetic field configurations.…”

Section: Introductionmentioning

confidence: 99%

Axial propagation of helicon waves

et al. 1995

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Traveling-and standing-wave characteristics of the wave fields have been measured in a helicon discharge using a five-turn, balanced magnetic probe movable along the discharge axis z. Helical and planepolarized antennas were used, and the magnitude and direction of the static magnetic field were varied, yielding three primary results. 1) As the density varies along z, the local wavelength agrees with the local dispersion relation. 2) Beats in the z variation of the wave intensity do not indicate standing waves but instead are caused by the simultaneous excitation of two radial eigenmodes. Quantitative agreement with theory is obtained.3)The damping rate of the helicon wave is consistent with theoretical predictions based on collisions alone.

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“…These fast electrons, which are necessary to ionize neutrals and sustain the plasma discharge against recombination and other losses, have been observed in some experiments [9], [5], [lo]. Figs.…”

Section: Helicon Source Modeling Resultsmentioning

confidence: 99%

“…Experimental evidence of Landau damping on bulk slow electrons and primary fast electrons at lower densities has been presented by Komori [4], Chen [5], and Loewenhardt [9], [lo]. Komori also showed that collisional damping 'is significant at high densities (ne 2 7 x 10I2 ~m -~) and plays an important role in transferring the energy to the electrons.…”

Section: Introductionmentioning

confidence: 89%

Modeling of profile effects for inductive helicon plasma sources

Mouzouris

Scharer

1996

IEEE Trans. Plasma Sci.

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Abstract-A computer code for modeling existing and new helicon sources for materials processing has been developed. The Nagoya type-111, helical, and Stix coil antennas have been modeled to study and examine plasma density and temperature profile effects on power absorption of a small fraction ( n f e / n e N 5%) of fast electrons (T,+,* N 40 eV) which provide ionization of the neutral gas in the experiment, and bulk (T,,1,, N 3 eV) electron distributions in an argon gas. The "ANTENA" computer code, originally written by B. McVey to study ion cyclotron waves, was modified and used to study and model helicon sources. A collisional model that includes radial density and temperature profiles was added to the code to study the effect of collisions on the heating mechanisms. The competing effects of collisional and Landau damping heating mechanisms have been investigated in detail, and results indicate that collisions play an important role in the plasma absorption profile at high densities (ne 2 1013 emp3).The radio frequency wave absorption profiles are sensitive to the plasma density and temperature profiles. The partial-turn helix antenna, that solely excites the m = +1 azimuthal mode, is found to be more efficient in coupling the power to an assumed plasma profile than the Nagoya type-111. The Stix coil is also found to be promising due to its on-axis peaking of the wave heating fields.

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Plasma production in a toroidal heliac by helicon waves

Cited by 94 publications

References 12 publications

Helicon wave excitation with helical antennas

Helicon wave excitation with helical antennas

Axial propagation of helicon waves

Modeling of profile effects for inductive helicon plasma sources

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