A powerful laser can redirect lightning strikes

Like a high-tech hammer of Thor, a strong laser can seize maintain of a lightning bolt and reroute its path via the sky.

In a mountaintop experiment, such a laser bent lightning towards a lightning rod, researchers report on-line January 16 in Nature Photonics. Scientists have used lasers to wrangle electrical energy within the lab earlier than, however that is the primary demonstration that the method works in real-world storms and will sometime result in higher safety in opposition to lightning.

At this time’s commonest anti-lightning tech is the traditional lightning rod, a meters-long metallic pole rooted to the bottom. The metallic’s conductivity lures in lightning which may in any other case strike close by buildings or folks, feeding that electrical energy safely into the earth. However the space shielded by a lightning rod is restricted by the rod’s peak.

“If you wish to shield some giant infrastructure, like an airport or a launching pad for rockets or a wind farm … then you definitely would want, for good safety, a lightning rod of kilometer measurement, or tons of of meters,” says Aurélien Houard, a physicist at Institut Polytechnique de Paris in Palaiseau, France. Such a tall metallic pole can be impractical. However a laser might attain that far, intercepting distant lightning bolts and ushering them all the way down to ground-based metallic rods.

Houard and his colleagues examined this concept atop the Säntis mountain in northeastern Switzerland. They arrange a high-power laser close to a telecommunications tower tipped with a lightning rod that’s struck by lightning round 100 occasions yearly. The laser was beamed on the sky for about six hours whole throughout thunderstorms from July to September 2021.

The laser blasted quick, intense bursts of infrared mild on the clouds about 1,000 occasions per second. This prepare of sunshine pulses ripped electrons off air molecules and knocked some air molecules out of its manner, carving out a channel of low-density, charged plasma. Form of like clearing a path via the woods and laying down pavement, this mix of results made it simpler for electrical present to move alongside this route (SN: 3/5/14). That created a path of least resistance for lightning to observe via the sky.

Houard’s group tuned their laser in order that it fashioned this electrically conductive pathway simply above the tip of the tower. This allowed the tower’s lightning rod to intercept a bolt snagged by the laser earlier than it zipped all the best way all the way down to the laser gear.

The tower was hit by lightning 4 occasions whereas the laser was on. A type of strikes occurred in a reasonably clear sky, permitting two high-speed cameras to seize the second. These photographs confirmed lightning zigzagging down from the clouds and following the laser mild for some 50 meters towards the tower’s lightning rod.

To trace the paths of the three bolts that they may not see, the researchers checked out radio waves shed by the lightning. These radio waves confirmed that the three strikes adopted the trail of the laser way more carefully than different strikes that occurred when the laser was off. This hinted that the laser guided these three strikes to the lightning rod, as effectively.

“It’s an actual achievement,” says Howard Milchberg, a physicist on the College of Maryland in School Park not concerned within the work. “Folks have been making an attempt to do that for a few years.” Scientists’ fundamental purpose in bending lightning to their will is to extend security, he says. However “if this factor ever grew to become actually, actually environment friendly, and the chance of guiding a discharge was elevated manner past what it’s now, it might probably even be helpful for charging issues up.”

Atmospheric and house scientist Robert Holzworth is extra cautious about imagining the functions. “They solely confirmed 50 meters of [guiding] size, and most lightning channels are kilometers lengthy,” says Holzworth, of the College of Washington in Seattle. So scaling the laser system as much as have a helpful attain might take a whole lot of work.

Utilizing a higher-frequency, higher-energy laser might prolong its attain, Houard says. “It is a first step towards a kilometric-range lightning rod.”