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Schlieren images of negative streamer and leader formations in CO2 and a CF3I-CO2 electronegative gas mixture

Widger, Phillip ORCID:, Hills, Meirion ORCID: and Mitchard, Daniel 2020. Schlieren images of negative streamer and leader formations in CO2 and a CF3I-CO2 electronegative gas mixture. Applied Sciences 10 (22) , 8006. 10.3390/app10228006

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In electrical networks, SF6 gas is currently used to insulate high-voltage equipment, however, due to its high environmental impact, new alternatives such as CO2 and electronegative gas mixtures such as CF3I-CO2 are being trialled to replace SF6 and create a sustainable energy system. A high-voltage lightning impulse (1.2 μs/50 μs) was used to approximate the disturbance in a high-voltage electrical network caused by a lightning strike and helped to identify the likely streamer and leader formations in different gases insulating a piece of gas insulated switchgear. In this paper, the theoretical and practical aspects of electrical streamer and leader formations in pure CO2 and an electronegative gas mixture of CF3I-CO2 are examined using schlieren videography in small length rod-plane gas gaps between 20 and 50 mm in length. Schlieren allows the examination of gas density in streamer formations and for the differences in weakly attaching gases, such as CO2, and electronegative gas mixtures, such as CF3I-CO2, to be studied. The gas pressure is varied in order to examine the differences in streamer and leader formation as the gas density is varied and hence the probability of electron collision is varied.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Additional Information: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution(CC BY) license (
Publisher: MDPI
ISSN: 2076-3417
Date of First Compliant Deposit: 12 November 2020
Date of Acceptance: 10 November 2020
Last Modified: 05 May 2023 22:39

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