Lightning conductor: Laser deflects lightning
A laser can apparently be used to create a kind of lightning conductor out of air. You just have to fire it often enough, a study on a Swiss mountain shows.
A laser can apparently guide lightning discharges to a lightning rod during a thunderstorm. This is suggested by the results of an international research group. If these indications are confirmed in further studies, this could lead to better lightning protection for airports, launch pads and large infrastructural facilities.The team led by Aurélien Houard from the Laboratoire d'Optique Appliquée in Palaiseau near Paris writes in the specialist journal "Nature Photonics".
The group installed the laser in the immediate vicinity of a 124-metre-high telecommunications tower on the Swiss mountain Säntis, which is struck by lightning around 100 times a year. They used a large number of sensors, including two high-speed cameras, to observe what was happening. During their six-hour campaign, they found evidence in four cases that lightning followed the path of the laser and then struck the top of the tower. She was even able to track one of them with the cameras.
The intense laser pulses would heat up the air along the beam, with the heat driving the air molecules out of this thin channel. The result is a so-called filament, which is more conductive than its surroundings due to its low air density, which is why it can serve as a favoured path for the lightning.
The use of lasers for lightning protection was proposed as early as 1974. The guidance of lightning by lasers was demonstrated in the laboratory at the end of the 1990s. However, outdoor trials failed in 2004 in the US state of New Mexico and in 2011 in Singapore. Houard's group attributes their success on Mount Säntis to the fact that their laser emits 1000 pulses per second - significantly more than in previous tests. This not only produces more stable filaments, but also increases the chance that the flash will hit such a channel at the right moment.
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Cover photo: TRUMPF/MARTIN STOLLBERG (AUSSCHNITT) / The research team wants to use a laser to increase the effective range of a lightning rod. Here, their lightning catcher shines on the summit of the Säntis
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