Tuesday, 15 Apr, 2008 Science

American scientists tested a new ultra-high-power laser which provokes lightning. Scientists fired ultra-fast pulses from an extremely powerful laser thus sending several terawatts into the clouds to call down electrical discharges in storm clouds over the region.

The beams sent from the laser made channels of ionized molecules, also known as "filaments." It is worth mentioning that before the lighting strikes earth the filaments lead electricity through the clouds, playing the role of lightning rods.

Researchers generated filaments that are too short-lived to trigger a real lightning strike. According to the French and German scientists, the fast pulses sent from the laser will be able to provoke thunder strikes on demand.

It is worth mentioning that for the first time the proposal of using laser to provoke thunderbolts was made in 1970s, but back then there has been no laser powerful enough to achieve the goal.

In laboratories scientists widely use powerful lasers that can create terawatts of energy. But to make an experiment outdoors, researchers applied a new type of laser, named Teramobile, created by a teem of engineers from France and Germany.

"This is the first laser that has terawatt power and is also mobile," outlined Andre Mysyrowicz, a researcher working at the Ecole Nationale Superieure de Techniques Avancees, Paris, France.

Researchers performed their experiment during a stormy weather. They placed the laser on top of South Baldy Peak in New Mexico. Scientists had the goal of provoking lightning strikes using an increasing rate of pulses sent from the terawatt laser and applying more complicated sequences of laser pulses.

Mr. Mysyrowicz explains that when the laser beam goes through the air, on its way to the cloud it becomes progressively more intense due to a process called "self-focusing." "The air acts like a succession of lenses, focusing the laser," mentioned Mysyrowicz.

The lightning strike is caused by the filaments of plasma, which a generated by the molecules ionized by air. The filaments of plasma reach a length of several hundreds of meters.

According to scientists, the main goal of provoking lightning is to deplete unpredictable storms before they cause chaos and destruction.

"Lightning control, if you want to protect particular sites, would be very useful. You could avoid lightning on very expensive or fragile sites," says Mysyrowicz.

Journal reference: Optics Express

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