TRUMPF/Martin Stolberg
Lightning rods protect buildings by providing a low-resistance path for electrical charges to flow between the cloud and the ground. However, it only works if the lightning bolt finds its path first. A real strike is chaotic and there are no guarantees that the process of initiating it will occur near the lightning rod and work as intended.
A team of European researchers decided they didn’t like its randomness and managed to safely aim several lightning strikes at a communication tower atop a mountain in Switzerland. A laser used to create a path for charged ions to smooth the path to the lightning rod.
laser makes everything better
A fundamental challenge in directing lightning is that atmospheric events that produce charged particles occur at significant altitudes compared to lightning rods. This allows lightning to find a path to the ground that does not use lightning rods. People managed to create a connection between the two by using a small rocket to launch a conductive cable to a height where there was an electrical charge. requires a large number of rockets and remains surrounded by cables.
The idea of using lasers to direct lightning is old, a proposal that first appeared in the scientific literature in the 1970s. A sufficiently high intensity laser beam has a complex relationship with the air it passes through. The changes it makes to the air help focus the laser, but the electrons it releases tend to scatter it. Creates a low pressure path in the laser wake. Critically, many of the particles stranded on these low-voltage filaments are electrically charged and can serve as pathways for lightning strikes.
We can also shape the laser pulse to control where these filaments start to form (up to 1 km away from the laser source).
But previous attempts to use lasers to direct lightning have had disappointing results. But disappointing results often fail to stop scientists from trying again (or at least force them to try again under the operating theory that all previous graduates are incompetent). increase). This explains why the research team ended up in the Swiss Alps and installed a high-power laser near the base of Säntis’s large communications tower.
Aside from frequency, the Tower is well equipped to study lightning, making it the perfect location for these experiments. The instrument measures the current flowing through the lightning rod and the electromagnetic field in its area, and can perform imaging at various wavelengths, including X-rays.
timing is everything
In any case, the researchers thought this time might be different for one main reason. Lasers have been greatly improved. They can now fire much more quickly. The one set up for this task is capable of 1 kilohertz frequencies. This is more than 100 times her rate of fire for lasers previously used for this kind of work. Researchers show that models involving this rapid circulation create more permanent filaments of charged particles in the air.
And it worked. Over six hours of testing, the tower received four hits while the lasers were active. One of these images of her, occurring in clear skies, clearly shows the lightning bolt traveling along the path defined by the laser until it reaches the tower.
Like almost all previously recorded lightning strikes on the Säntis tower, all four lightning strikes originated from the ground and propagated upwards. However, 85% of the attacks recorded there are associated with negative charge pools in the cloud. In contrast, all four laser-induced strikes were connected to positively charged pools.
The researchers’ modeling indicates that this charge orientation facilitates bridging the gap between the tower and the laser-generated filament, reinforcing the idea that these four attacks were indeed laser-guided. I’m here.
This doesn’t mean you can randomly summon lightning bolts if you want or suck all the risk out of the clouds. All of these attacks were related to nearby thunderstorm activity, and the tower was struck several times by bolts unrelated to the laser’s path. Still, the study offers prospects for the potential for controlled experimental research using lightning. This seems to strongly defy its chaotic nature. And these experiments could serve you safely in the long run.
nature photonics, 2023. DOI: 10.1038/s41566-022-01139-z (About DOI).
