Helicon waves and efficient plasma production

Komori, A.; Shoji, T.; Miyamoto, Ko Ichiro; Kawai, Jun; Kawai, Yoshinobu

doi:10.1063/1.859846

Cited by 105 publications

(58 citation statements)

References 8 publications

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“…Bulk temperature profiles showed little radial variation, consistent with other helicon measurements. 27 The magnetic field probe was inserted into the plasma at a radius of 3.25 cm. Careful simultaneous measurements of the axial plasma density profile and wave B z field were made to minimize the effects of probe perturbations on the plasma and wave characteristics.…”

Section: Resultsmentioning

confidence: 99%

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

et al. 2004

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Helicon waves are excited in a plasma wave facility by a half-turn double-helix antenna operating at 13.56 MHz for static magnetic fields ranging from 200 to 1000 G. A non-perturbing optical probe located outside the Pyrex™ plasma chamber is used to observe 443 nm Ar II emission that is spatially and temporally correlated with the helicon wave. The Ar II emission is measured along with wave magnetic and Langmuir probe density measurements at various axial and radial positions. 105 GHz interferometry is used to verify the bulk temperature corrected Langmuir probe measurements. The measured peak Ar II emission phase velocity is compared to the measured wave magnetic field phase velocity and code predicted wave phase velocity for the transition and blue mode regimes. Very different properties of the optical emission peak phase and wave characteristics for the transition and helicon modes of operation are observed. Comparison of the experimental results with the ANTENAII code ͓Y. Mouzouris and J. E. Scharer, IEEE Trans. Plasma Sci. 24, 152 ͑1996͔͒ is carried out for the wave field measurements for the two regimes of operation.

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Section: Resultsmentioning

confidence: 99%

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

et al. 2004

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“…As Helicon discharges can typically be operated at very low pressures (e. g. 0.03 Pa [3]) but this must be verified for the ITER reference source setup. If the pressure can be reduced, the over-all efficiency of the NNBI system could be increased as the stripping losses of H − due to collisions with the gas would be reduced.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Helicon discharges as RF coupling concept of negative hydrogen ion sources

Briefi

Fantz

2013

AIP Conference Proceedings

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Abstract. The ITER reference source for H − and D − requires a high RF input power (up to 90 kW per driver). To reduce the demands on the RF circuit, it is highly desirable to reduce the power consumption while retaining the values of the relevant plasma parameters namely the positive ion density and the atomic hydrogen density. Helicon plasmas are a promising alternative RF coupling concept but they are typically generated in long thin discharge tubes using rare gases and an RF frequency of 13.56 MHz. Hence the applicability to the ITER reference source geometry, frequency and the utilization of hydrogen/deuterium has to be proved. In this paper the strategy of the approach for using Helicon discharges for ITER reference source parameters is introduced and the first promising measurements which were carried out at a small laboratory experiment are presented. With increasing RF power a mode transition to the Helicon regime was observed for argon and argon/hydrogen mixtures. In pure hydrogen/deuterium the mode transition could not yet be achieved as the available RF power is too low. In deuterium a special feature of Helicon discharges, the socalled low field peak, could be observed at a moderate B-field of 3 mT.

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“…Despite the substantial experimental interest in these sources, [1][2][3][4][5][6][7][8] no detailed two-dimensional (r,z) plasma profile wave simulations have been carried out to date to better model and understand propagation and absorption mechanisms. 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.…”

Section: Introductionmentioning

confidence: 99%

Wave propagation and absorption simulations for helicon sources

Mouzouris

Scharer

1998

Physics of Plasmas

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A two-dimensional ͑2-D͒, finite-difference computer code is developed to examine helicon antenna coupling, wave propagation, collisionless Landau, and collisional heating mechanisms. The code calculates the electromagnetic wave fields and power absorption in an inhomogeneous, cold, collisional plasma. The current distribution of the launching antenna, which provides the full antenna spectra, is included in the model. An iterative solution that incorporates warm plasma thermal effects has been added to the code to examine the contribution of collisionless ͑Landau͒ wave absorption by electrons. Detailed studies of the wave fields and electron heating profiles at low magnetic fields (B 0 Ͻ100 G), where both Trivelpiece-Gould ͑TG͒ and helicon ͑H͒ modes are present, are discussed. The effects of the applied uniform magnetic field (B 0 ϭ10-1000 G), 2-D (r,z) density profiles (n e0 ϭ10 11 -10 13 cm Ϫ3 ), neutral gas pressures of 1-10 mTorr and the antenna spectrum on collisional and collisionless wave field solutions and power absorption are investigated. Cases in which the primarily electrostatic ͑TG͒ surface wave dominates the heating and the power is absorbed near the edge region and cases in which the propagating helicon wave transports and deposits its energy in the core plasma region are examined.

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Helicon waves and efficient plasma production

Cited by 105 publications

References 8 publications

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

Optical, wave measurements, and modeling of helicon plasmas for a wide range of magnetic fields

Investigation of Helicon discharges as RF coupling concept of negative hydrogen ion sources

Wave propagation and absorption simulations for helicon sources

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