Plasma and Fusion Research

Volume 3, 055 (2008)

Rapid Communications

Dramatic Enhancement of OH(A2Σ+) Density in a Recombining Hydrogen Plasma
Kanji SHIBAGAKI, Renge ASAKAWA, Daiyu HAYASHI1) and Koichi SASAKI2)
Department of Electrical and Electronic Engineering, Suzuka National College of Technology,Suzuka, Mie 510-0294, Japan
1)
Philips Technology Research Laboratories, Weisshausstr. 2, 52066 Aachen, Germany
2)
Plasma Nanotechnology Research Center, Nagoya University, Nagoya 464-8603, Japan
(Received 21 June 2008 / Accepted 19 August 2008 / Published 2 October 2008)

Abstract

Optical emission spectra in the wavelength range of molecular hydrogen were observed in both ionizing and recombining plasma modes of hydrogen discharges. The optical emission spectrum from the ionizing plasma was dominated by the Fulcher-α system (a3Σg+ - d3Πu-) of molecular hydrogen. On the other hand, the optical emission spectrum from the recombining plasma was composed of many lines, and was completely different from the spectrum of the ionizing plasma. The many peaks observed from the recombining plasma were assigned to the X2Π - A2Σ+ transition of OH. The OH(A2Σ+) is thought to originate from the chemical etching of a glass discharge tube by atomic hydrogen. This is analogous to the interaction between a detached divertor plasma and a graphite plate, and a possible process for the enhancement of OH(A2Σ+) density in a recombining plasma is discussed with this analogy in mind.

Keywords

optical emission spectroscopy, molecular spectroscopy, recombining plasma

DOI: 10.1585/pfr.3.055

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This paper may be cited as follows:

Kanji SHIBAGAKI, Renge ASAKAWA, Daiyu HAYASHI and Koichi SASAKI, Plasma Fusion Res. 3, 055 (2008).