Understanding Lightning from the Lab: Initiation, Propagation, and X-ray Emissions

Description du projet

La vérité surprenante sur la physique de la foudre

La foudre reste l’un des plus grands mystères de la nature. Nous ne pouvons toujours pas expliquer avec précision comment un éclair se forme dans les hauteurs d’un nuage d’orage ni pourquoi il émet des rayons X, dont l’énergie dépasse largement les prévisions théoriques. Le projet Bottled Lightning, financé par le CER, vise à construire une immense chambre de décharge unique en son genre afin de recréer un orage en miniature. En contrôlant minutieusement l’atmosphère et en laissant tomber des particules semblables à de la glace à travers des champs électriques intenses et variables, les chercheurs envisagent de déclencher et de maintenir des flashs artificiels avec une grande reproductibilité. À l’aide d’impulsions de tension qui surpassent de plusieurs ordres de grandeur les expériences existantes, l’équipe identifiera les mécanismes d’allumage et suivra la propagation des décharges leaders. Cela permettra de faire passer notre compréhension de ce phénomène violent du stade théorique à celui de résultats de laboratoire quantifiables.

Objectif

Despite the huge impact of lightning, its fundamental properties are still very poorly understood. With this project I want to build an infrastructure of carefully designed laboratory experiments in a novel physical regime, that will provide the conditions required to understand lightning phenomena. I will use this to answer some of the major open questions in lightning and high voltage discharge research. I will provide major scientific breakthroughs to answer the questions on 1) how lightning is initiated, 2) how lightning propagates by so-called leaders and 3) how these leaders emit energetic radiation (X-rays). The experiments will be complemented by dedicated numerical simulations for the best interpretation.
Initiation of lightning within thunderclouds involves a complex, yet not understood interplay between electric fields, ice particles, charges and cosmic rays. I will have ice-like particles fall through varying electric fields in the novel discharge chamber and observe when discharges form and when they are strong enough to initiate lightning.
Once initiated, lightning propagates through so-called leader discharges, but the exact mechanism has only been hypothesized. I want to understand how this is controlled by streamer discharges around it. During inception and propagation, lightning emits X-rays and other energetic radiation with energies far above expected electron energies. I will pinpoint the location and mechanism of such emissions with high reproducibility.
The experiments will be unique in the world, due to the large discharge chamber, its highly controlled atmosphere, and its accompanying pulse source surpassing existing experiments by orders in voltage risetime and amplitude. This will expose new physical phenomena and thereby lead to great insights and uses: for the lightning community, validation of simulations and theories and understanding of lightning radio emissions, and for high voltage engineers tools to improve their devices.