WASHINGTON (Reuters) – When Benjamin Franklin made his first lightning rod in the 1750s after famously experimenting with flying a kite with a switch attached during a thunderstorm, the American inventor had no way of knowing that it would remain state of the art. for centuries.
Scientists are now moving to improve an 18th-century innovation with 21st-century technology—a system using high-energy lasers that may revolutionize lightning protection. Researchers said Monday they have successfully used a laser pointed into the sky from the top of Mount Santis in northeastern Switzerland to deflect lightning strikes.
With further development, this Laser Lightning Rod can protect critical infrastructure including power plants, airports, wind farms and launch pads. Lightning causes billions of dollars in damage to buildings, communication systems, power lines, and electrical equipment annually while also killing thousands of people.
The equipment was hauled to the top of the mountain at about 8,200 feet (2,500 metres), some parts using a gondola and others by helicopter, and focused into the sky above 400 feet (124 metres). A tower belonging to the telecommunications provider Swisscom (SCMN.S)one of the European structures most affected by lightning.
In two-month trials in 2021, it fired intense laser pulses — 1,000 times a second — to redirect lightning strikes. All four strikes were successfully intercepted when the system was active. In the first case, the researchers used two high-speed cameras to record the redirection of the lightning’s path more than 160 feet (50 meters) away. Three more are documented with different data.
“We have shown for the first time that lasers can be used to guide natural lightning,” said physicist Aurelien Houard of the Laboratory of Applied Optics at Ecole Polytechnique in France, coordinator of the Laser Lightning Rod project and lead author of the research published in the journal. Nature photonics.
Lightning is a high-voltage electrical discharge between a cloud and the ground, within a cloud or between clouds.
“In its trajectory, the intense laser can generate long columns of plasma in the atmosphere with electrons, ions, and particles of hot air,” Howard said, referring to positively charged particles called ions and negatively charged particles called electrons.
“Here we have shown that these plumes of plasma can act as lightning guides,” Howard added. “It’s important because it’s the first step toward laser-based lightning protection that can actually reach hundreds of meters (yards) or 1 kilometer (0.6 miles) high with sufficient laser power.”
The laser is the size of a large car and weighs more than 3 tons. It uses lasers from German industrial machine maker Trumpf Group. With University of Geneva scientists also playing a key role, the experiments were carried out in collaboration with the airline ArianeGroup, a European joint venture between Airbus SE (AIR.PA) and Safran SA (SAF.PA).
This concept, first proposed in the 1970s, has been successful in laboratory conditions, but so far not in the field.
Lightning rods, dating back to Franklin’s time, are metal rods on top of buildings, connected to the ground with wire, that conduct lightning electric charges to the ground. Its limitations include protecting only a small area.
Howard predicted that 10 to 15 years of additional work would be required before the Laser Lightning Rod would come into common use. One concern is to avoid interference with aircraft in flight. In fact, air traffic in the area came to a halt when the researchers used the laser.
“In fact, there is a potential problem with using the system with air traffic in the area because the laser can damage a pilot’s eye if they pass the laser beam and look down,” Howard said.
Reporting by Will Dunham; Editing by Lisa Shumaker
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