A super laser as a lightning rod
Lightning strikes cause damage of several billion euros around the world each year. They lead to power outages and forest fires, they damage computer systems, and they can kill people and animals. Scientists assume that heavy thunderstorms will increase due to climate change.
Ever since 1752 when Benjamin Franklin was struck by his brain wave of experimenting with a metal kite people have known how to protect themselves against the destructive fury of thunderbolts. The experiment inspired the American inventor and statesman with the idea of equipping the roofs of buildings with long metal tips that would intercept the electrical discharges and conduct them into the ground. Lightning rods have been serving this purpose all over the world until today – even 270 years after the kite experiment.
Lightning “teased out” from the clouds
However, lightning rods are not always of help. Especially in the case of large buildings with sensitive technical systems such as airports and power-plants they do not provide adequate protection. Moreover, lightning rods may even trigger additional indirect effects such as electromagnetic interferences and voltage surges in equipment. That’s why the EU launched the Laser Lightning Rod (LLR) project. The idea behind it is a laser gun “teasing out” lightning from the clouds, specifically channeling and diverting it from costly infrastructure in order to conduct it from there into the ground.
While the idea itself has been around for some time, no laser meeting its demands has existed up to now. The project requires a laser with one terawatt (one billion watts) of peak pulse power. For comparison: one of the most powerful laser pointers has a power output of 50 watts and a range of 40 kilometers (25 miles).
The LLR project partners at the University of Geneva and the laser specialists of the technology company Trumpf have been testing the laser system weighing five metric tons (5.5 short tons) on Mount Säntis in Switzerland since this summer. Per second, the super laser shoots 1,000 ultra-short laser pulses into the atmosphere, generating a seemingly infinitely long ionized channel, a so-called laser filament, in the direction of the clouds. This channel is said to provide a preferred pathway for lightning.
“If we use lasers in the right way, we could eliminate the damage caused by lightning strikes in the future.”Prof. Jean-Pierre Wolf, University of Geneva
Eliminating the risks of thunderclouds
“The filaments trigger discharges, and the lightning follows the channels. So, in addition to triggering lightning, we can also cause it to discharge in a certain direction,” says Prof. Jean-Pierre Wolf from the University of Geneva. As a result, the risk of thunderclouds can be eliminated in two ways: the laser either discharges the cloud until it’s calm or it guides the lightning to a standard lightning conductor on the ground.
Using satellite data, a research team has identified the places on Earth with the highest incidence of lightning. The worldwide record is held by Lago de Maracaibo in Venezuela, where flashes of lightning on average occur in an area of one square kilometer (0.4 square miles) on 297 days a year. Africa is the front runner among continents, with 283 of the 500 top lightning hotspots located there.