uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
A study of NOx production in air heated by laser discharges: Effect of energy, wavelength, multiple discharges and pressure
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
2008 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 40, no 1, 208-214 p.Article in journal (Refereed) Published
Abstract [en]

An experimental study on the production of NOX in air heated under the action of a concentrated laser beam is presented. In this experiment laser induced plasma was produced in air in a closed Teflon chamber of inner volume 1600 cm3 by focusing a laser beam with either the wavelength of 1064 or 532 nm from a Q-switched Nd:YAG laser. The NOX production was measured by chemiluminescence method and the possible effect of wavelengths, multiple discharges, and pressure on the yield of NOX was studied. The results show that within the studied plasma energy range of 26-253 mJ for 532 nm beam and 16-610 mJ for 1064 nm beam, the NOX production scales linearly with the dissipated plasma energy. For a given energy, 532 nm beam produces more NOX in air at atmospheric pressure than the 1064 nm beam. In an attempt to see the possible influence of multiple discharges on the production of NOX, discharges were created using 2-8 pulses with a repetition rate of 10 pulses per second in stationary air at atmospheric pressure. The results indicate that a certain amount of the NOX created by a given pulse is destroyed by the subsequent pulses. In order to study the pressure dependence of the NOX production, the pressure was varied from 16 to 100 kPa in the chamber and it was found that the NOX production efficiency scales linearly with pressure.

Place, publisher, year, edition, pages
2008. Vol. 40, no 1, 208-214 p.
Keyword [en]
Laser induced plasma, Lightning, Nitrogen oxides
National Category
Engineering and Technology Meteorology and Atmospheric Sciences
Research subject
Engineering Science with specialization in Atmospheric Discharges
Identifiers
URN: urn:nbn:se:uu:diva-93602DOI: 10.1016/j.optlastec.2007.01.007ISI: 000250258800024OAI: oai:DiVA.org:uu-93602DiVA: diva2:167130
Available from: 2005-10-06 Created: 2005-10-06 Last updated: 2016-04-19
In thesis
1. NOx Production by Ionisation Processes in Air
Open this publication in new window or tab >>NOx Production by Ionisation Processes in Air
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The study presented in this thesis was motivated by the large uncertainty on the concentration of atmospheric electrical discharges to the global nitrogen budget. This uncertainty is partly due to the fact that information concerning the NOx production efficiency of electrical discharges having current signatures similar to those of lightning flashes is not available in the literature. Another reason for this uncertainty is the fact that energy is used as a figure of merit in evaluating NOx production from lightning flashes even though insufficient knowledge is available concerning the energy dissipation in lightning flashes. The third reason for this uncertainty is the lack of knowledge concerning the contribution of discharge processes other than return strokes to the NOx production in the atmosphere. Lightning is not the only process in the atmosphere that causes ionisation and dissociation of atmospheric air. Cosmic rays continuously bombard the Earth with high energetic particles and radiation causing ionization and dissociation of air leading to the production of NOx in the atmosphere. The work carried out in this thesis is an attempt to improve the current knowledge on the way in which these processes contribute to the global NOx production. Experiments have been conducted in this thesis to estimate the NOx production efficiency of streamer discharges, laser-induced plasma, laboratory sparks having current signatures similar to those of lightning flashes, alpha particle impact in air and finally with the lightning flash itself. The results obtained from laboratory electrical discharges show the following: (a) The NOx production efficiency, in terms of energy, of positive streamer discharges is more or less similar to those of hot discharges. (b) The NOx production efficiency of an electrical discharge depends not only on the energy but also on the peak and the shape of the current waveform. (c) The current signature is a better figure of merit in evaluating the NOx yield of electrical discharges. As a part of this thesis work a direct measurement of NOx generated by lightning flashes was conducted and the results show that slow discharge processes such as continuing currents could be the main source of NOx in lightning flashes. Concerning NOx production by other ionisation processes such as alpha particle impacts in the atmosphere, the data gathered in this thesis show that each ionising event in air leads to the creation of one NOx molecule. In terms of energy the NOx production efficiency of alpha particles is similar to that of electrical discharges. The theoretical studies conducted within this thesis indicate that M-components contribute more than the return strokes to the NOx production. The calculations also show that the contribution to the global NOx budget by return stroke is not as high as that assumed in the current literature.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. 35 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 104
Keyword
Engineering physics, Nitrogen oxides, Lightning, Electrical Discharges, Cosmic Rays, Troposphere, Teknisk fysik
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:uu:diva-6016 (URN)91-554-6370-3 (ISBN)
Public defence
2005-10-28, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00
Opponent
Supervisors
Available from: 2005-10-06 Created: 2005-10-06 Last updated: 2016-04-29Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Rahman, MahbuburCooray, Vernon

Search in DiVA

By author/editor
Rahman, MahbuburCooray, Vernon
By organisation
Division for Electricity and Lightning Research
In the same journal
Optics and Laser Technology
Engineering and TechnologyMeteorology and Atmospheric Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 526 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf