A team of European researchers and scientists said Monday they have successfully guided lightning with a laser beam for the first time, hoping the method will help people avoid deadly lightning strikes and maybe even cause them in the future.
Worldwide, lightning strikes 40 to 120 times per second, killing more than 4,000 people every year and causing billions of dollars in damage.
But the lightning rod, invented by American polymath Benjamin Franklin in 1749, remains the main defense against these air bolts.
For years, a group of scientists from six research institutes have been trying to use the same concept, but using a far more complex and accurate laser instead of the simple metal rod.
Now, in a study just published in the journal Nature Photonics, they explain the use of a laser beam shot from the top of a Swiss mountain to deflect a bolt of lightning more than 50 meters.
Aurelien Houard, a physicist at the Department of Applied Optics at the ENSTA Institute in Paris and lead author of the study, explained: “We wanted to provide the first evidence that the laser can have an effect on lightning and that it is the easiest to avoid.” to steer.
But for future applications, “it would be even better if we could trigger lightning,” Houard said.
How do you catch lightning?
Static energy accumulated in storm clouds or between clouds and the ground is released as lightning. Plasma generated by the laser beam heats the air with charged ions and electrons.
According to Houard, the air “becomes partially conductive and consequently a path favored by lightning”. In a similar experiment conducted by scientists in New Mexico in 2004, their laser failed to catch the flash.
According to Houard, this laser failed because it didn’t generate enough pulses per second to ignite a flash, which it does in milliseconds. It’s also a challenge to “predict where Lightning will land,” he continued.
For the latest experiment, the scientists left little to chance. They towed a car-sized laser capable of firing up to a thousand pulses of light per second at the 2,500-meter-high Säntis summit in north-eastern Switzerland.
There is a transmission tower on the summit, which is struck by lightning about 100 times a year. The construction of the powerful laser took two years and the transport in sections by cable car took many weeks. In the end, the huge containers that were supposed to hold the telescope had to be dropped off by helicopter.
The telescope focused the laser beam to a maximum intensity at a point about 150 meters up just above the top of the 124-meter-long tow. The jet initially has a diameter of 20 centimeters, but narrows to a few centimeters at the tip.
Ride the Lightning
The researchers captured an image of their jet moving lightning 50 to 60 meters during a storm in the summer of 2021. Interferometric tests showed that three other impacts were also controlled.
Most lightning bolts develop from precursors within the clouds, but if the electric field is strong enough, some bolts can also rise from the ground. “Once the earth is connected to the cloud, the current and power of lightning becomes really apparent,” Houard added.
One of those predecessors is guided by the laser, making it “much faster than the others and straighter,” the scientist claimed. Then, before it lights up, it will be the first to connect to the cloud. This means that this technique could theoretically be used not only to drive away lightning, but to trigger it in the first place.
That could allow scientists to better protect strategic facilities like airports or missile launch pads by detonating strikes at the time of their choosing. In practice, this would require a high level of conductivity in the laser’s plasma, which the scientists do not yet believe can be mastered.
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