E-H mode transition in low-pressure inductively coupled nitrogen-argon and oxygen-argon plasmas

Lee, Young Wook; Lee, Hye Lan; Chung, T. H.

doi:doi:10.1063/1.3587156

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Electrodynamic force of dielectric barrier discharge

The periodic electrostatic force of dielectric barrier discharge (DBD) in nitrogen for flow control is investigated by a system of physics-based, two-dimensional model equations. The plasma generation process of DBD is mainly the avalanche growth of electrons through the secondary emission from cathode. Therefore, the charged particle motion of a succession of random micro discharges can be approximated by the drift-diffusion model. The force of DBD generated by charge separation and accumulati...

Internal structure of 0.9 GHz microplasma

Argon microplasmas generated at 0.9 GHz by a split-ring resonator form a single filament-shaped nonequilibrium glow discharge. The internal structure of these microplasmas is probed using laser diode absorption and imaging emission spectrometry. These two-dimensional diagnostics are then Abel inverted to reveal that the core of the filament has a strongly depleted central metastable argon population. The microdischarges are approximately 0.2 mm in width at 1 atm and expand with increasing input...

This work investigates the characteristics of the E-H mode transition in low-pressure inductively coupled N₂-Ar and O₂-Ar discharges using rf-compensated Langmuir probe measurements and optical emission spectroscopy (OES). As the ICP power increases, the emission intensities from plasma species, the electron density, the electron temperature, and the plasma potential exhibit sudden changes. The Ar content in the gas mixture and total gas pressure have been varied in an attempt to fully characterize the plasma parameters. With these control parameters varying, the changes of the transition threshold power and the electron energy distribution function (EEDF) are explored. In N₂-Ar and O₂-Ar discharges at low-pressures of several millitorr, the transition thresholds are observed to decrease with Ar content and pressure. It is observed that in N₂-Ar plasmas during the transition, the shape of the EEDF changes from an unusual distribution with a flat hole near the electron energy of 3 eV in the E mode to a Maxwellian distribution in the H mode. However, in O₂ -Ar plasmas, the EEDFs in the E mode at low Ar contents show roughly bi-Maxwellian distributions, while the EEDFs in the H mode are observed to be nearly Maxwellian. In the E and H modes of O₂-Ar discharges, the dissociation fraction of O₂ molecules is estimated using optical emission actinometry. During the E-H mode transition, the dissociation fraction of molecules is also enhanced.

Article Outline

INTRODUCTION
EXPERIMENT
SPATIALLY AVERAGED MODEL
RESULTS AND DISCUSSION
CONCLUSION

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KEYWORDS and PACS

Keywords

argon, discharges (electric), dissociation, Langmuir probes, nitrogen, oxygen, plasma density, plasma instability, plasma temperature

PACS

52.35.Qz

Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
52.25.Os

Emission, absorption, and scattering of electromagnetic radiation
52.70.Ds

Electric and magnetic measurements
52.80.-s

Electric discharges

ARTICLE DATA

Digital Object Identifier

http://dx.doi.org/10.1063/1.3587156

PUBLICATION DATA

ISSN

0021-8979 (print)

1089-7550 (online)

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American Institute of Physics

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