Scientists said on Monday that they have successfully guided lightning for the first time using a laser beam. They believe the method will one day be used to both cause and prevent lethal lightning strikes. Worldwide, lightning strikes 40–120 times per second, killing more than 4,000 people each year and incurring billions of dollars in damage. Yet the lightning rod, which was invented by American polymath Benjamin Franklin in 1749, continues to be the primary defense against these aerial bolts.
Since years, a group of scientists from six research institutes has been attempting to use the same concept but utilize a much more complex and precise laser in place of the simple metal pole. Now, they explain utilizing a laser beam—shot from the peak of a Swiss mountain—to guide a lightning bolt for more than 50 meters in a study that was just published in the journal Nature Photonics.
Aurelien Houard, a physicist at the ENSTA Paris institute’s applied optics department and the study’s principal author, stated, “We wanted to deliver the first demonstration that the laser may have an affect on lightning—and it is simplest to steer it. However, Houard told AFP that “it would be much better if we could trigger lightning” for upcoming applications.
How to catch lightning
Static energy that has accumulated in storm clouds or between clouds and the ground releases itself as lightning. Plasma, which is produced by the laser beam, heats the air with charged ions and electrons. According to Houard, the air turns “partially conductive, and consequently a path favoured by the lightning.” In a similar experiment, conducted by scientists in New Mexico in 2004, their laser failed to capture the lightning. According to Houard, the reason why that laser failed was because it did not create enough pulses per second for lightning, which brews in milliseconds..
It was also challenging to “predict where the lightning was going to fall,” he continued. The scientists didn’t take many chances with their most recent experiment. They carried a car-sized laser up the 2,500-meter peak of the Santis mountain in northern Switzerland. This laser can fire up to a thousand pulses of light per second. A communications tower on the top experiences lightning strikes about 100 times annually. The strong laser took two years to construct, and many weeks to transport it via cable car in sections.
The enormous containers that would hold the telescope had to be dropped off by helicopter at the end. The telescope concentrated the laser beam at a point approximately 150 meters in the air—just above the summit of the 124-meter tower—where it was at its strongest. The beam is 20 centimeters in diameter at the bottom and only a few centimeters in diameter at the top.
Ride the lightning
The researchers captured a shot of their beam pushing a lightning bolt 50 meters during a storm in the summer of 2021. Interferometric measurements revealed that three further impacts were steered as well. The majority of lightning develops from precursors inside the clouds, however if the electric field is strong enough, some lightning may also rise from the ground.
“Once the ground is connected to the cloud, the current and strength of a lightning bolt really become obvious,” Houard added. One of these precursors is guided by the laser, which makes it “far faster than the others—and straighter,” he claimed. Then, before it turns on, it will be the first to connect with the cloud. This indicates that, theoretically, this method may be used to both provoke lightning and drive it away.
By starting strikes at specific times, scientists might be able to better defend vital infrastructure, such as airports or rocket launch pads. That would necessitate a plasma with a high conductivity in practice, which scientists do not believe they have yet perfected.
Reference: Nature Photonics , https://techxplore.com/, Aurélien Houard, Laser-guided lightning, Nature Photonics (2023). DOI: 10.1038/s41566-022-01139-z. www.nature.com/articles/s41566-022-01139-z
