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

Descrizione del progetto

La sconvolgente verità sulla fisica dei fulmini

Il fulmine rappresenta tuttora uno dei misteri più profondi della natura: non siamo infatti ancora in grado di spiegare esattamente come venga innescato da un’alta nube temporalesca o perché emetta raggi X, energie di gran lunga superiori alle aspettative teoriche. Il progetto Bottled Lightning, finanziato dal CER, si propone di costruire una camera di scarica unica e immensa al fine di ricreare un temporale in miniatura. Controllando attentamente l’atmosfera e facendo cadere particelle simili al ghiaccio attraverso campi elettrici intensi e variabili, i ricercatori intendono innescare e sostenere lampi artificiali caratterizzati da un’elevata riproducibilità. Utilizzando impulsi di tensione che superano di ordini di grandezza gli esperimenti esistenti, il team individuerà i meccanismi di accensione e seguirà le modalità di propagazione delle scariche principali, facendo in tal modo passare la comprensione di questo fenomeno violento dalla teoria al campo dei risultati di laboratorio quantificabili.

Obiettivo

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.