Aachen PK 2003 – scientific programme
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P: Plasmaphysik
P 18: Plasma Wall Interaction
P 18.5: Talk
Friday, March 21, 2003, 11:50–12:10, FO1
Influence of wall materials at different temperatures on the vibrational population of molecular hydrogen — •S. Meir1,2, U. Fantz1, and K. Behringer1,2 — 1Lehrstuhl für Experimentelle Plasmaphysik, Institut für Physik, Universität Augsburg, D-86135 Augsburg — 2Max-Planck-Institut für Plasmaphysik, D-85748 Garching, EURATOM Association
The vibrational population in the ground state
of molecular hydrogen is a key parameter in hydrogen discharges
since it enhances the formation of negative hydrogen ions, the
ionisation and dissociation rate coefficients. Furthermore the
electron energy distribution function will be modified. Besides
the volume processes the vibrational population can be affected
by surface processes, either by direct reflection of molecular
hydrogen or by recombining hydrogen atoms or ions at the target.
In order to measure the influence of different materials on the
vibrational population, additional surfaces (carbon, tungsten,
copper, aluminium; steel and quartz as reference) have been
installed in the chamber of a planar inductively coupled plasma.
The vibrational population was determined by emission
spectroscopy of the Fulcher transition which is sensitive for the
first four to five vibrational levels. The results for the
different materials and the plasma without additional surface are
compared. Since the chamber walls are cooled, the influence of
the target temperature is investigated by cooling and heating the
additional surface actively.