Science

Scientists guide lightning bolts with laser beams for first time

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The Laser Lightning Rod is beamed near the top of a tower on the summit of Säntis, in the Swiss Alps
UNIGE Martin Stollberg
The Laser Lightning Rod is beamed near the top of a tower on the summit of Säntis, in the Swiss Alps
UNIGE Martin Stollberg
A model constructed from data of an experiment with the Laser Lightning Rod, where the bolt can be clearly seen following the laser beam for a while before reaching the tower
Xavier Ravinet - UNIGE

Lightning rods have been used to guide lightning strikes for centuries, but now scientists have demonstrated something a bit more advanced than a humble metal stick. Beaming a high-powered laser into the sky was shown to deflect lightning bolts, which could lead to laser lightning rods that protect a wider area from dangerous strikes.

Lightning is one of the most energetic natural events, unleashing millions of volts in fractions of a second. That of course can be destructive, damaging buildings, cutting power, starting fires and causing injuries and deaths.

For centuries our best defense against lightning strikes has been the lightning rod, a simple metal stick attached to tall buildings that attracts the electricity and guides it safely to the ground. But they have limited range – a 10-m (33-ft) lightning rod can protect an area of just 10 m around itself. To protect a building as big as say an airport or wind farm would require unfeasibly large lightning rods.

Now, researchers in Europe have demonstrated a more effective new system. The Laser Lightning Rod (LLR) involves, as the name suggests, beaming a laser into the clouds during a storm to forge a path of least resistance for the electricity to flow through. And it can extend much further than a lightning rod.

“When very high power laser pulses are emitted into the atmosphere, filaments of very intense light form inside the beam,” said Jean-Pierre Wolf, last author of the study. “These filaments ionize the molecules of nitrogen and oxygen present in the air, which then release free electrons to move. This ionized air, called ‘plasma’, becomes an electrical conductor.”

To demonstrate the concept, the scientists developed a new laser system with an average power of 1 kW, pulsing about 1,000 times per second while unleashing one Joule of energy per pulse. This was set up on the summit of Säntis, in the Swiss Alps, near a tower that attracts about 100 lightning strikes every year.

Between June and September 2021, the team tested the system during storms that swept through the area. The laser was beamed into the sky near the top of the tower, to try to coax the lightning to the beam before it reached the tower’s regular lightning rod. During that summer, four lightning strikes hit the tower while the laser was switched on, and sure enough it bent the bolt.

A model constructed from data of an experiment with the Laser Lightning Rod, where the bolt can be clearly seen following the laser beam for a while before reaching the tower
Xavier Ravinet - UNIGE

“We found, from the first laser lightning event, that the discharge could follow the beam for almost 60 m (197 ft) before reaching the tower, thus increasing the radius of the protection surface from 120 m to 180 m (394 to 590 ft),” said Wolf.

The idea of using lasers as lightning rods has been around for a long time, and has shown promise in lab experiments, but the team says that this is the first time it’s been demonstrated out in the real world. Other scientists have proposed that graphene tractor beams could do the job even better, but that would require more complex setups.

The eventual goal of the LLR project is to use a laser to extend a 10-m lightning rod’s influence by 500 m (1,640 ft), the team says.

The research was published in the journal Nature Photonics. The team describes the work in the video below.

Source: UNIGE

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6 comments
Claudio
And what happens if the bolt does NOT deflect to the rod, following the laser to the emitter?
I can already hear a loud bang and a stinky smell of fried electronics... ;-)
michael_dowling
𝐜𝐥𝐚𝐮𝐝𝐢𝐨: Lightning tends to follow the path of least resistance,so it would prefer hitting the metal rod rather than following the beam to it's source. I have a couple of concerns with this device. One,it is a 1 kilowatt beam,which would be instantly blinding if it struck someone out in the storm,which could occur if the beam reflected off a Mylar chip bag blowing in the wind,for example. The cockpit of an aircraft flying high over the site could be struck by the beam,which would be very dangerous for the vision of the pilots,much more dangerous than someone on the ground waving a laser pointer.
FB36
Imagine using laser to guide/direct Taser shots to create ray-guns/rifles/cannons!
Claudio
@michael_dowling I'm familiar with the physics involved in this kind of event; what prompted my question is the fact that the behavior of the bolts is sometimes erratic, I wouldn't bet my monies on the the fact that "it would prefer hitting the metal rod rather than following the beam to its source". In fact, it rather reminds me of one of the Wile E. Coyote's experiments...
joe46
@FB36 experiments were done decades ago doing something along those lines, what they did was fired a high powered, pulsed laser at a target (non-human) and fed a high voltage discharge (from a Tesla coil, or something to that effect) into the laser and the "lightning bolt" streamed along the laser and earthed itself on the target. so this experiment with lightning specifically maybe new, but the basic idea is nothing new.
P51d007
Now if they can figure out a way to capture and harness that energy.