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Optical emission spectra of high current and high voltage generated arcs representing lightning

Mitchard, D., Widger, P., Clark, D., Carr, D. and Haddad, A. 2019. Optical emission spectra of high current and high voltage generated arcs representing lightning. Applied Physics Letters 114 (16) , 164103. 10.1063/1.5092875
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Abstract

A recently developed spectrographic technique was used for the comparison of observed optical emission spectra from self-breakdown in air of high current and high voltage impulse arcs which are often used to represent the respective components of a natural lightning strike for a variety of lightning studies. These components are separated as it is practically impossible to simultaneously generate both in a single arc within the laboratory. The high current aspect is typically related to the amount of damage a lightning arc does to an impacted object and can be used to characterize conductivity properties, whereas the high voltage aspect is typically related to the attachment mechanism of lightning to an object when creating a path to ground and can be used to characterize insulation properties. The spectra of a range of high current arcs up to 100 kA and high voltage arcs up to 120 kV across a 14 mm air-gap between a pair of hemispherical tungsten electrodes were investigated and compared with the natural lightning reference spectrum reconstructed from the literature. All three spectra were found to present similar trends, but the high voltage arc had notably lower blackbody radiation, indicating a less energetic and cooler arc. Further, whereas atomic lines from oxygen and nitrogen were clearly present, an atomic line from argon was not prominent, indicating that the bulk energy delivered into the air was in the range of 1400–1520 kJ/mol. The high current arc, much like natural lightning, delivered a bulk energy greater than 1520 kJ/mol.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Engineering
Publisher: AIP Publishing
ISSN: 0003-6951
Date of First Compliant Deposit: 16 May 2019
Date of Acceptance: 7 April 2019
Last Modified: 17 May 2019 22:46
URI: http://orca.cf.ac.uk/id/eprint/122503

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