Production and loss of rovibrationally excited H2 molecules: Expanding hydrogen plasmas in experiment and model

O.G. Gabriel, P.J.W. Vankan, D.C. Schram, R.A.H. Engeln

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademic

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Abstract

The rovibrationally resolved density distributions of molecular hydrogen are measured in expanding thermal hydrogen plasmas by means of laser induced fluorescence in the vacuum-UV range (VUV-LIF). The results reveal a non-Boltzmann distributions, where the low rotational states (J = 1-6) follow a temperature of 700 K, while the higher rotational states are overpopulated compared to these lower states and follow higher temperatures up to 4500 K. Experiments were performed under variation of the surface area in the plasma source by varying the nozzle length. We assume surface association processes of atomic hydrogen at the surface of the nozzle, producing rovibrationally excited H2 molecules. While the atomic hydrogen flow decreases with increasing surface areas, the H2 rv distribution shows a more pronounced non-Boltzmann behaviour. A simple 0D model of (de)excitation processes by collisions with electrons and neutrals results in additional information about the formation of the measured H2 rv distributions.
Original languageEnglish
Title of host publicationXXVIII International Conference on Phenomena in Ionised Gases (ICPIG 2007) 15-20 July 2007, Prague, Czech Republic. Proceedings
EditorsJ. Schmidt, M. Simek, S. Pekarek, V. Prukner
Place of PublicationBristol, United Kingdom
PublisherInstitute of Physics
Pages132-134
ISBN (Print)9788087026014
Publication statusPublished - 2007

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