The damage posed by lightning strikes to humans and structures is well mediated by the lightning rod invented by Benjamin Franklin in 1752. This conductive metal mast protects a surface with a radius equivalent to its height, but as the height of these devices is not limitlessly extendable, they are not optimal for protecting wide areas, such as an airport or nuclear power plant. A laser-based solution developed by an international research consortium promises to significantly increase the radius of the protection surface.

The Laser Lightning Rod (LLR) generates channels of ionized air to guide lightning along its beam.The LLR is beamed near the top of a 124 m-high telecommunication tower. Source: Martin Stollberg/University of Geneva Extending upward from a traditional lightning rod, the device can be used to extend the height of a traditional lightning rod as well as the surface of the area it is protecting.

The LLR is 1.5 m wide, 8 m long, weighs more than 3 tons, and incorporates a new laser with an average power of 1 kW, one Joule per pulse and a duration per pulse of one picosecond. The terawatt laser was tested at a height of 2,502 m and was focused above a 124 m transmitter tower equipped with a traditional lightning rod. The laser was activated every time storm activity was forecast between June 2021 and September 2021.

The field experiments demonstrated that lightning discharge could follow the laser beam for almost 60 m before reaching the tower, thus increasing the radius of the protection surface from 120 m to 180 m. The goal of the LLR project detailed in Nature Photonics is to use a laser to extend a 10 m lightning rod’s influence by 500 m.

Researchers from Ecole Polytechnique (France), University of Geneva (Switzerland), Agency for Science Technology and Research (Singapore), Ecole Polytechnique Fédérale de Lausanne (Switzerland), TRUMPF Scientific Lasers GmbH (Germany), New Mexico Institute of Mining and Technology, ArianeGroup (France), Swisscom Broadcast AG (Switzerland), Uppsala University (Sweden) and University of Applied Sciences and Arts Western Switzerland (Switzerland) contributed to this illuminating development.