Researchers developed a laser beam lightning rod

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There’s a reason lightning rods haven’t changed much since Benjamin Franklin’s literally electrifying 18th century experiments—they work pretty well as is. Typically composed of a metal rod anchored directly into the ground via metal cabling, the simple, scalable device directs lightning bolts that are often five-times hotter than the sun’s surface into the Earth, where the charge can safely dissipate.

Still, lightning strikes can cause billions of dollars of infrastructural damage each year, leading one research team in Switzerland to recently develop a breakthrough method in diverting the electrical discharges away from sensitive structures. In essence, the scientists propose firing extremely powerful laser beams into the heart of a thunderstorm.

[Related: How to prevent a lightning strike.]

As detailed on Monday in the research journal Nature Photonics, alongside rundowns from The Guardian and elsewhere, the group of scientists recently set up a laser array near a 124m telecom tower atop Switzerland’s Säntis mountain. The structure is the recipient of over a hundred lightning strikes annually, making it a prime attractor for the experiment. Between July and September of last year, the lasers fired into a number of stormfronts over a total of six hours. According to researchers’ measurements, the laser pulses influenced the course of four upward discharges, although only one took place in clear enough conditions to photograph using high-speed cameras. Still, the lightning’s path in that instance appears to have been diverted around 50m towards the laser beam.

The system works thanks to the lasers’ ability to forge a more convenient path for lighting to travel towards the Earth. The surrounding air’s refractive index changes as the pulses fire at over 1,000 times per second into the storm clouds, making them contract and intensify so much that they ionize surrounding air molecules. A channel of ionized, low density air is then created from the air molecules quickly heating and spreading at supersonic speeds. Although these “filaments” as researchers describe them only last mere milliseconds, their conductivity compared to surrounding air make a much easier path for lightning arcs. Early indications also point to the laser lightning rods’ diversion range being much wider than traditional metal rods, which ostensibly cover an area about twice as wide as the rod is tall.

[Related: A new energy weapon combines multiple laser beams.]

There are some immediate drawbacks to this new system, however. For one, the laser pulses are (perhaps unsurprisingly) extremely bright, and could easily pose issues for any potential nearby pilots—hence closing the airspace around the experiment during its runtime. Then there’s the system’s roughly $2 million price tag during the experiment’s five year development that eventually saw the enlisting of Switzerland’s largest helicopter to help build the laser system’s home atop Säntis. All of that makes it very unlikely to see laser lightning rods atop suburban homes thanks to the  comparatively very cheap land-based rod.

That said, such a system could be more cost-effective for places like military bases, extremely tall structures, and spaceports with generally far more expensive repair costs than the average home following lightning strikes.



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