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Scientists used a huge laser to deflect beams

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Scientists have managed to create a virtual lightning rod using a large, powerful laser on top of a mountain in Switzerland, successfully deflecting the path of lightning.

Lightning deflection technology hasn’t changed much since Ben Franklin invented the lightning rod in 1752. Franklin’s rod, or a pointed metal pole atop buildings and other structures vulnerable to lightning, works by intercepting lightning and guiding the rays safely to earth.

But the zone of protection for Franklin rods is relative to their height – a lightning rod with a height of 10 meters (32.8 feet) protects an area with a radius of 10 meters.

As the height of lightning rods is not infinite, large areas such as airports, launch pads, power stations, wind farms and nuclear power plants pose a challenge. Lightning causes up to 24,000 deaths a year year and could cause power outages, wildfires and damage to infrastructure, according to a study detailing the findings published Monday in the journal Nature Photonics.

Scientists decided to test whether a laser beam aimed at the sky could act as a large, mobile virtual lightning rod. Previous research has supported the idea that laser pulses can influence the path of rays, but this work has only been done inside a laboratory.

A laser the size of a large car was installed near a telecommunications tower on the summit of Mount Säntis in northeastern Switzerland. Lightning strikes the tower about 100 times a year.

Researchers activated the laser during the summer of 2021 for more than six hours in storm events between June and September. The Laser Lightning Rod, as it is called by members of the European consortium that developed it, managed to deflect four beams.

The laser was focused above a 124 meter high (406.8 ft) transmitter tower belonging to Swisscom, which has a traditional lightning rod attached to it.

High-speed cameras recorded the attacks and further observations were made using high-frequency electromagnetic waves created by the lightning, as well as X-ray bursts connected to the attacks.

“When high-powered laser pulses are emitted into the atmosphere, very intense light filaments form within the beam,” study co-author Jean-Pierre Wolf, professor of applied physics at the University of Geneva, said in a statement.

“These filaments ionize the nitrogen and oxygen molecules in the air, which then release free electrons to move. This ionized air, called plasma, becomes an electrical conductor.”

The laser’s energized particle channels helped guide the lightning along the laser beam. The laser was capable of firing up to 1,000 pulses per second.

The Laser Lightning Rod weighs over 3 tons, is 1.5 meters (4.9 feet) wide and 8 meters (26.2 feet) long.

The device was tested at a height of 2,502 meters (8,208 feet) on top of Mount Säntis and was designed by TRUMPF scientific lasers based in Munich, Germany to operate even under difficult weather conditions such as fog that often floats around. from the top of the mountain.

A beam followed the laser beam for several tens of meters before hitting the tower (in red and white), according to the scientists.

“The main difficulty was that it was a full-size campaign. We had to prepare an environment in which we could install and protect the laser,” said study co-author Pierre Walch, a doctoral student at Laboratoire d’Optique Appliquée, a joint research unit from the Polytechnic Institute of Paris, the French National Center for Scientific Research, École Polytechnique and ENSTA Paris, in a statement.

Each time storm activity was predicted around the mountain during the experiment, the area was closed to air traffic.

“The aim was to see if there was a difference with or without the laser,” said study lead author Aurélien Houard, a researcher at Laboratoire d’Optique Appliquée, in a statement. “We compared the data collected when the laser filament was produced above the tower and when the tower was struck naturally by lightning.”

The research team worked for almost a year to analyze the data collected during the experiment.

“From the first beam using the laser, we found that the discharge could follow the beam for almost 60 meters (196 feet) before hitting the tower,” said Wolf, “meaning it increased the radius of the protection surface from 120 meters (393 feet) to 180 meters (590 feet).

Next, the research team wants to increase the laser’s capability by extending its range and protection zone in hopes that it can one day be used as a traditional alternative to wide-area lightning rods.