LIGHTNING RESEARCH : ADJUNCT TO LIGHTNING ROD : ADVANCED TECHNOLOGY
Smithsonian Mag : William Sullivan Report : January 18, 2023
The technology could one day protect wider areas than metal lightning rods do, perhaps shielding airports and launchpads during storms.
For the first time, scientists have diverted lightning by using lasers. On the Säntis mountai
n in northeastern Switzerland, they shot rapid-fire beams of light into the sky and successfully guided lightning for 50 meters.
With this success as proof-of-concept, lasers could one day protect large infrastructure such as airports and launchpads from lightning strikes, write the researchers in a paper published Monday in Nature Photonics.
“The achievement is impressive given that the scientific community has been working hard along this objective for more than 20 years,” Stelios Tzortzakis, a laser physicist at the University of Crete in Greece who did not contribute to the research, tells Nature News’ Elizabeth Gibney. “If it’s useful or not, only time can say.”
Lightning strikes can damage structures and threaten human life. They are responsible for billions of dollars of damage each year, according to the study, and killed nearly 450 people in the United States between 2006 and 2021.
Currently, protection against lightning strikes hinges on the lightning rod, an 18th century invention credited to Benjamin Franklin. Made of metal and typically placed atop structures, lightning rods attract bolts and guide the current into the ground before it can cause damage.
But these physical rods can only shield a limited area. “If you have a ten-meter-high traditional lightning rod, it protects a region with a radius of about ten meters, which is fine for your house, but clearly not enough for an airport that is probably a few kilometers long,” study co-author Jean-Pierre Wolf, a physicist at the University of Geneva, tells the Wall Street Journal’s Aylin Woodward. “So, the idea is we replace this metallic stick with a laser that is kind of a longer, virtual rod that can be put in the direction you want and be switched on or off at any time.”
Since a laser beam can extend much higher than a physical rod, it can widen the protected area on the ground. The quick pulses of lasers generate heat and push some surrounding air molecules out of the way. This creates a path made of lower-density air that conducts electricity and channels the lightning.
Scientists have been considering using lasers to guide lightning since the 1960s. But while researchers had used lasers to guide electricity in a laboratory, they were unable to do so with lightning outdoors, until now.
In the recent experiment, the scientists set up a laser next to a Swiss telecommunications tower fitted with a lightning rod, which is struck by lightning around 100 times each year. The laser fired rapid pulses of light upward at about 1,000 times per second. This speed, researchers say, enabled their success—previous experiments that used fewer pulses per second had failed.
During the summer of 2021, the team operated the laser for around six hours in total, during which the beams diverted lightning to the rod four times. Evidence from radio antennas and high-speed cameras shows that during these strikes, the bolt followed the laser beam’s path for about 50 meters before reaching the lightning rod.
“It is the first realization of something that we’ve been dreaming of for decades,” Matteo Clerici, a physicist at the University of Glasgow who didn’t contribute to the new study, tells the Wall Street Journal. “The fact that they managed to do it in an outdoor environment is a very big step.
But before lasers can be practically used in this way, they need to be able to guide lightning for longer distances, Robert Holzworth, an atmospheric and space scientist at the University of Washington who did not contribute to the study, says to Science News’ Maria Temming. “They only showed 50 meters of [guiding] length, and most lightning channels are kilometers long,” he tells the publication.
A laser also comes with a much higher cost than a lightning rod: Aurélien Houard, a paper co-author and physicist at the École Polytechnique in France, tells the Wall Street Journal that the laser cost more than $2 billion and won’t be commercialized for at least a decade.
“We’re a long ways away from having the technology to keep everybody safe from lightning,” Joseph Dwyer, a physicist at the University of New Hampshire who wasn’t involved in the research, tells the Washington Post’s Joel Achenbach.
Smithsonian Mag : William Sullivan Report : January 18, 2023
