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
On Dimensions of Atmospheric-Pressure Hollow Cathodes
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research. (Elektricitetslära)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Elektricitetslära)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Elektricitetslära)
2007 (English)In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 35, no 3, 522-526 p.Article in journal (Refereed) Published
Abstract [en]

The hollow cathode is known as a source of high-density plasmas. This property is due to the hollow-cathode effect (HCE), which can be explained by the oscillations of fast electrons between repelling potentials of opposing space-charge sheaths. At atmospheric pressure, one should be able to create an HCE by adjusting the dimension of the hollow cathode. Experiments show that the dimensions could be as large as 500, so that the sheath thickness may be on the order of 100. Theoretical models of the atmospheric-pressure sheaths based on the conventional Child-Langmuir approach give the sheath thicknesses on the order of 10, which contradicts the experiments. We introduce here a new model which takes into account three groups of electrons: slow, fast, and secondary. By adding a group of fast and secondary electrons, we show that the sheath thickness increases as compared with only slow electrons present.

Place, publisher, year, edition, pages
2007. Vol. 35, no 3, 522-526 p.
Keyword [en]
Atmospheric pressure, hollow cathode, radio frequency (RF), sheaths
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-97235DOI: 10.1109/TPS.2007.897894ISI: 000247352900001OAI: oai:DiVA.org:uu-97235DiVA: diva2:172077
Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2016-04-11Bibliographically approved
In thesis
1. Modelling and Applications of the Hollow Cathode Plasma
Open this publication in new window or tab >>Modelling and Applications of the Hollow Cathode Plasma
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents experimental and modelling research on atmospheric pressure hollow cathodes and hollow electrodes. Experiments with the hybrid hollow electrode activated discharge (H-HEAD), which is a combination of a hollow cathode and a microwave plasma source, is presented. The experiments show that this source is able to produce long plasma columns in air and nitrogen at atmospheric pressure and at very low gas flow rates. Measurements of the vibrational temperature of the nitrogen molecules are also presented in this thesis. The vibrational temperature is an indication of the electron temperature in the plasma, an important characteristic of the plasma. Modelling work on the hollow cathode at atmospheric pressure with fluid equations is also presented. It is shown that the inclusion of fast and secondary electrons, characteristic of the hollow cathode plasmas, increases the sheath width. The sheath width was found to be of the order of 100 μm. By modelling the plasma as highly collisional by using the drift-diffusion approximation, it was shown that the increase in sheath thickness was larger at lower pressures than at higher pressures. Still, the sheath width can be of the order of 100 μm. A pulsed atmospheric plasma in a hollow electrode geometry was also modelled by the drift-diffusion fluid equations, with the addition of the energy equation for electrons. Rate and transport coefficients for the electrons were calculated from the solution to the Boltzmann equation as functions of mean electron energy. The dynamics of the plasma at pulse rise time showed large electron density and mean energy peaks at the cathode ends, but also that these quantities were enhanced at the centre of the discharge, between the cathode plates.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 87 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 433
Keyword
Engineering physics, hollow cathode, hybrid plasma, vibrational temperature, atmospheric pressure, fluid modelling, radio frequency, pulsed power, Teknisk fysik
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:uu:diva-8747 (URN)978-91-554-7206-1 (ISBN)
Public defence
2008-05-28, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:30 (English)
Opponent
Supervisors
Available from: 2008-05-07 Created: 2008-05-07 Last updated: 2010-04-23Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Söderström, DanielBaránková, HanaBárdos, Ladislav

Search in DiVA

By author/editor
Söderström, DanielBaránková, HanaBárdos, Ladislav
By organisation
Division for Electricity and Lightning ResearchElectricity
In the same journal
IEEE Transactions on Plasma Science
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 529 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