Scientists use high-power laser to divert lightning strikes

Washington: When Benjamin Franklin fashioned the first lightning rod in the 1750s following his famous experiment flying a kite with a key attached during a thunderstorm, the American inventor had no way of knowing this would remain the state of the art for centuries.

Scientists now are moving to improve on that 18th century innovation with 21st century technology – a system employing a high-powered laser that may revolutionise lightning protection. Researchers said on Monday they succeeded in using a laser aimed at the sky from atop Mount Santis in north-eastern Switzerland to divert lightning strikes.

With further development, this laser lightning rod could safeguard critical infrastructure including power stations, airports, wind farms and launchpads. Lightning inflicts billions of dollars in damage on buildings, communication systems, power lines and electrical equipment annually while also killing thousands of people.

The equipment was hauled to the mountaintop at an altitude of about 2500 metres, some parts using a gondola and others by helicopter, and was focused on the sky above a 124-metre-tall transmission tower belonging to telecommunications provider Swisscom, one of Europe’s structures most affected by lightning.

In experiments during two months in 2021, intense laser pulses – 1000 times per second – were emitted to redirect lightning strikes. All four strikes while the system was active were successfully intercepted. In the first instance, the researchers used two high-speed cameras to record the redirection of the lightning’s path by more than 50 metres. Three others were documented with different data.

“We demonstrate for the first time that a laser can be used to guide natural lightning,” said physicist Aurelien Houard of Ecole Polytechnique’s Laboratory of Applied Optics in France, coordinator of the Laser Lightning Rod project and lead author of the research published in the journal Nature Photonics.

Lightning is a high-voltage electrical discharge between a cloud and the ground, within a cloud or between clouds.

“An intense laser can generate on its path long columns of plasmas in the atmosphere with electrons, ions and hot air molecules,” Houard said, referring to positively charged particles called ions and negatively charged particles called electrons.