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Velocity of Laboratory Electrical Discharges at low Pressure
Division for Electricity, Uppsala University.ORCID iD: 0000-0002-6375-6142
Division for Electricity, Uppsala University.
2006 (English)Conference paper, Abstract (Refereed)
Abstract [en]

One of the most important characteristics of sprite development is the velocity of the downward tendrils, which has been observed to range from 105 to 3x107 m/s (Moudry et al., JGR, 29, 2002). However, there is a lack of laboratory experimental data on the speed of propagation of electrical discharges at pressures similar to those encountered in the sprite environment. In order to gather more information on this topic, the average velocity of propagation of electrical discharges in quasi-uniform electric fields in air at pressures ranging from 1 to 10 mBar has been measured from optical emission. In the laboratory, the discharge is confined in a glass tube of 0.09 m diameter and between the electrodes placed 0.8 m apart. Each electrode has an equivalent radius of 0.25 m and is segmented into two concentric sections, one of them placed inside the tube. The voltage impulses applied to the cathode and the anode have a risetime of about 20 ns and a decay (half-value) time of 2 ms. The light from the discharge is detected with two optical fibers connected to photomultipliers Hamamatsu R1477-06, placed at 0.05 m from the electrodes. For each considered pressure, a set of impulse voltages with increasing peak values are applied. The lowest voltage applied at a particular pressure corresponds to the voltage for which light signals are detected. The average development velocities of the discharges at 1, 4 and 10 mBar are estimated from the measured optical signatures. For the considered pressures, the measured discharge velocity ranged from 1.5x105 to 1.5x107 m/s for reduced electric fields E/N (where E is the average electric field and N is the gas density) ranging from 120 to 1200 Td. This range of measured discharge velocities correspond to observed velocities of downward tendrils in sprites. In addition, a well-defined empirical relationship as given below, is found between the reduced discharge velocity v/N and the reduced electric field E/N in the range of pressures considered: v/N=102.002log(E/N)-5.234 [10-6 m4/s]

Place, publisher, year, edition, pages
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-74196OAI: diva2:489289
American Geophysical Union, Fall Meeting 2006. San Francisco, CA, USA. 11–15 December 2006
QC 20120530Available from: 2012-02-02 Created: 2012-02-02 Last updated: 2012-05-30Bibliographically approved

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Becerra, Marley
Electrical Engineering, Electronic Engineering, Information Engineering

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