1. High‐Speed Video Observation of a Dart Leader Producing X‐rays.
- Author
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Saba, M. M. F., Ferro, M. A. S., Cuadros, E. T., Custódio, D. M., Nag, A., Schumann, C., Cooray, V., Paiva, A. R., Lauria, P. B., Medeiros, D. S. F., Hettiarachchi, P., and Rassoul, H. K.
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X-rays ,HIGH-speed video recording ,LIGHTNING ,ELECTRIC fields ,ELECTRIC conductivity - Abstract
This work presents the first simultaneous X‐ray measurement and high‐speed video observation of the propagation of a lightning leader producing X‐rays. As a result, the three‐dimensional leader distance from the X‐ray measurement and, for the first time, the conditions of the preexisting channel during the leader propagation were observed. Although four leaders in this seven‐stroke flash followed the same path to ground, X‐rays were only observed during the leader before the return stroke with the highest peak current. The fact that the other three leaders following the same path to ground did not produce detectable X‐rays confirms the hypothesis that leader line charge density is an important factor that determines X‐ray production. The fact that X‐rays was recorded only when the leader tip was at a certain portion of the lightning channel confirms that the orientation of the leader plays an important role in the detection of X‐rays. Plain Language Summary: It was known that lightning can produce X‐rays. However, in this study, thanks to the use of a high‐speed video camera it was possible to determine when lightning produces X‐rays, how far it was, how it was oriented when the detection of X‐rays, and what the conditions of the preexisting channel were during the leader propagation. The observations of the present work allow for new insights, confirmation of some hypotheses, and comparison with past studies. The results presented help to understand why X‐rays are sometimes detected and sometimes not. It is shown that the amount of charge transferred by the discharge plays a crucial role. This study also confirms that the orientation of the descending leader plays an important role in the detection of X‐rays. Key Points: First high‐speed video observation of a natural lightning leader producing X‐rays during its propagation to groundExperimental confirmation that the production of X‐rays depends on the leader charge density in natural lightningThe orientation of the leader plays an important role in the detection of X‐rays [ABSTRACT FROM AUTHOR]
- Published
- 2019
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