Emission spectroscopy of a microhollow cathode discharge plasma in helium-water gas mixtures

Journal Article · Sat Oct 01 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3646551· OSTI ID:22036733

Namba, S; Yamasaki, T; Hane, Y; Fukuhara, D; Kozue, K; Takiyama, K ^[1]

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1. Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan)

A dc microhollow cathode discharge (MHCD) plasma was generated inflowing helium gas containing water vapor. The cathode hole diameters were 0.3, 0.7, 1.0, and 2.0 mm, each with a length of 2.0 mm. Emission spectroscopy was carried out to investigate the discharge mode and to determine the plasma parameters. For the 0.3-mm cathode, stable MHCDs in an abnormal glow mode existed at pressures up to 100 kPa, whereas for larger diameters, a plasma was not generated at atmospheric pressure. An analysis of the lineshapes relevant to He at 667.8 nm and to H{alpha} at 656.3 nm implied an electron density and gas temperature of 2 x 10{sup 14} cm{sup -3} and 1100 K, respectively, for a 100-kPa discharge in the negative glow region. The dependence of the OH band, and H{alpha} intensities on the discharge current exhibited different behaviors. Specifically, the OH spectrum had a maximum intensity at a certain current, while the H atom intensity kept increasing with the discharge current. This observation implies that a high concentration of OH radicals results in quenching, leading to the production of H atoms via the reaction OH + e{sup -}{yields} O + H + e{sup -}.

• OSTI ID: 22036733
• Journal Information: Journal of Applied Physics, Vol. 110, Issue 7; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
74 ATOMIC AND MOLECULAR PHYSICS
ATOMS
CATHODES
ELECTRIC CURRENTS
ELECTRON DENSITY
ELECTRON TEMPERATURE
ELECTRONS
EMISSION SPECTROSCOPY
GLOW DISCHARGES
HELIUM
HYDROXYL RADICALS
ION TEMPERATURE
MIXTURES
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA INSTABILITY
PLASMA PRESSURE
WATER VAPOR