Diagnostic techniques for atmospheric streamer discharges

Pictures show that streamer or sprite discharge channels emerging from the same electrode sometimes seem to reconnect or merge though their heads carry electric charge of the same polarity; one might therefore suspect that reconnections are an artefact of the two-dimensional projection in the pictures. Here we use stereo photography to investigate the full three-dimensional structure of such events. We analyse reconnection, possibly an electrostatic effect in which a late thin streamer reconnects to an earlier thick streamer channel, and merging, a suggested photoionization effect in which two simultaneously propagating streamer heads merge into one new streamer. We use four different anode geometries (one tip, two tips, two asymmetric protrusions in a plate and a wire), placed 40 mm above a flat cathode plate in ambient air. A positive high voltage pulse is applied to the anode, creating a positive corona discharge. This discharge is studied with a fast ICCD camera, in many cases combined with optics to enable stereoscopic imaging. We find that reconnections as defined above occur frequently. Merging on the other hand was only observed at a pressure of 25 mbar and a tip separation of 2 mm, i.e. for a reduced tip distance of p · d = 50 µm bar. In this case the full width at half maximum of the streamer channel is more than 10 times as large as the tip separation. At higher pressures or with a wire anode, merging was not observed.

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“…This value is in agreement with streamer observations in a wire-plane geometry of Winands et al [22] and Creyghton et al [23].…”

Section: Mergingsupporting

confidence: 92%

Reconnection and merging of positive streamers in air

Nijdam¹,

Geurts²,

Veldhuizen³

et al. 2009

J. Phys. D: Appl. Phys.

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“…Specifically we are interested in the distribution of the streamers in the reactor, because the high-energy electrons and therefore the radicals needed for air-purification processes are generated in the streamer head and the path of the streamer [28,29,30,31,32,33,34]. Therefore, the distribution of the streamers in the reactor directly influences the chemical activity in the reactor.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the distribution of the streamers in the reactor directly influences the chemical activity in the reactor. However, when the streamers cross the gap between the electrodes, secondary streamers can form [5,6,30,35]. The electrons in the secondary streamers are less energetictypically only 1-2 eV as compared to 5-10 eV for primary streamers -and consequently the radical generation in these streamers is different than in primary streamers [6,5].…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporally resolved imaging of streamer discharges in air generated in a wire-cylinder reactor with (sub)nanosecond voltage pulses

Huiskamp

Sengers²,

Beckers

et al. 2017

Plasma Sources Sci. Technol.

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• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Huiskamp, T., Sengers, W., Beckers, F. J. C. M., Nijdam, S., Ebert, U. M., van Heesch, E. J. M., & Pemen, A. J. M. (2017). Spatiotemporally resolved imaging of streamer discharges in air generated in a wire-cylinder reactor with (sub)nanosecond voltage pulses. Plasma Sources Science and Technology, 26(7), 075009. DOI: 10.1088/1361-6595/aa7587General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Abstract. We use (sub)nanosecond high-voltage pulses to generate streamers in atmospheric-pressure air in a wire-cylinder reactor. We study the effect of reactor length, pulse duration, pulse amplitude, pulse polarity, and pulse rise time on the streamer development, specifically on the streamer distribution in the reactor to relate it to plasma-processing results. We use ICCD imaging with a fully automated setup that can image the streamers in the entire corona-plasma reactor. From the images, we calculate streamer lengths and velocities. We also develop a circuit simulation model of the reactor to support the analysis of the streamer development. The results show how the propagation of the high-voltage pulse through the reactor determines the streamer development. As the pulse travels through the reactor, it generates streamers and attenuates and disperses. At the end of the reactor, it reflects and adds to itself. The local voltage on the wire together with the voltage rise time determine the streamer velocities, and the pulse duration the consequent maximal streamer length.Spatiotemporally resolved imaging of streamer discharges in air generated in a wire-cylinder reactor with (sub

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“…In the air under atmospheric pressure, the radiative transition probabilities for N 2 and N 2 þ are mainly affected by the non-radiative collisional quenching by nitrogen and oxygen molecules. The modified radiative transition probabilities in air were published by Creyghton et al (1994). The mean electron energy and electric field strength dependent on the ratio of luminescence intensities I(N 2 )/I(N 2 + ) were successfully calculated by Creyghton et al (1994) and Kim et al (2003).…”

Section: Mean Electron Energy and Electric Field Strengthmentioning

confidence: 99%

“…The modified radiative transition probabilities in air were published by Creyghton et al (1994). The mean electron energy and electric field strength dependent on the ratio of luminescence intensities I(N 2 )/I(N 2 + ) were successfully calculated by Creyghton et al (1994) and Kim et al (2003). Evaluations of mean electron energy and electric field strength using the calculation methodology presented by Kim et al (2003) gave an electron energy range from 6 to 8 eV and electric field strength from 70 to 90 kV cm -1 for the experimental conditions used in this study.…”

Section: Mean Electron Energy and Electric Field Strengthmentioning

confidence: 99%

Generation of Active Oxidant Species by Pulsed Dielectric Barrier Discharge in Water-Air Mixtures

Kornev

Yavorovsky

Preis

et al. 2006

Ozone: Science & Engineering

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Experimental research into the electrical and optical parameters of pulsed dielectric barrier discharge (PDBD) was undertaken. PDBD was applied to humid air containing water droplets as a means of water oxidative treatment with short-living species generated in the discharge zone. In spectral analysis of PDBD, only small concentrations of nitric oxides were detected at the resulting electric field strength and electron mean energy sufficient for generation of OH-radicals. The water droplets served as electric field strength concentrators: PDBD was ignited close to the water droplets' surface.

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Diagnostic techniques for atmospheric streamer discharges

Cited by 32 publications

References 12 publications

Reconnection and merging of positive streamers in air

Reconnection and merging of positive streamers in air

Spatiotemporally resolved imaging of streamer discharges in air generated in a wire-cylinder reactor with (sub)nanosecond voltage pulses

Generation of Active Oxidant Species by Pulsed Dielectric Barrier Discharge in Water-Air Mixtures

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