Modellierung des dynamischen Verhaltens von Oberflächen-Barrierenentladungen und der Ozonerzeugung

Surface discharges, as a special kind of barrier discharges, occur in arrangements with small but extended high-voltage electrodes on one side of a dielectric layer and a plane counter electrode on its reverse side. Surface discharges are used e. g. in excimer lamps, in plasmadisplays, for surface treatment of plastic foils and for plasma-chemical applications like ozone production. This work has the aim to model the dynamics of surface discharges and to simulate the spatial and temporal resolved discharge development in oxygen and air at atmospheric pressure. The discharge development is investigated at negative and positive polarity of the surface electrode as well as at AC voltage. Based on the results of the discharge simulation the ozone generation in surface discharge arrangements is analysed. The simulation results reveal a stepwise development of the discharge on the dielectric surface at both polarities in good agreement with experimental findings. In each discharge step, the accumulation of charge carriers on the dielectric surface leads to a reduction of the field strength and the decay of the discharge step. At increased voltage a further step can develop. The discharge development at negative polarity is dominated by a cathode fall mechanism at the metallic surface electrode. In the cathode fall a maximum reduced field strength of about 2400 Td is found. The propagation of the discharge along the dielectric surface is combined with a field strength maximum of about 260 Td at the tip of the discharge. At positive polarity a positive streamer propagates along the dielectric surface in each discharge step. At the streamer head, a maximum reduced field strength of about 700 Td is found. In the streamer channel the field strength drops to about 10 Td. A cathode fall is found as well, which appears near the streamer head on the dielectric surface and has comparable properties as that with negative polarity. The results of a spatial resolved simulation of the plasma-chemical processes in air show, that especially in areas with high field strengths nitrogen is dissociated as well as oxygen. At negative polarity this happens in the cathode fall, at positive polarity at the streamer head. Because of local over-temperatures of up to 80 K found at both polarities nearby the surface electrodes, nitrogen oxides are produced, which destroy effectively ozone in catalytic reaction chains. This may explain the low efficiency of the ozone production from air with surface discharges in comparison with a conventional discharge arrangement with a gas gap.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2002

Author dc:creator

• Humpert, Christof

Contributors dc:contributor

• Pietsch, Gerhard J.

• info:eu-repo/classification/ddc/530
• Physik
• Barrierenentladung
• Gleitentladung
• Ozongewinnung

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123779%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:62191