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"Long
before it's in the papers"
April 14, 2008
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Step toward man-made lightning reported
April 14, 2008
Courtesy Optical Society of America
and World Science staff
In what they call a first step toward conveniently triggering artificial lightning, scientists say they have touched off electric discharges in thunderclouds by shooting powerful lasers at them. Lightning near Tucson,
Ariz. (Image courtesy NOAA)
“We generated lighting precursors,” said Jérôme Kasparian of the University of Lyon in France, one of the researchers.
Creating lightning is an important tool for studying the mechanisms of lightning and testing the lightning resistance of airplanes and infrastructure, added Kasparian and colleagues.
Scientists have been able to trigger lightning strikes since the 1970s by shooting small rockets, spooling long wires behind them, into thunderclouds. But only about half these attempts work, said Kasparian and colleagues. Laser technology, they added,
could make the process easier, cheaper and could open up new applications.
Lightning still isn’t fully understood, though it been studied since the times of Benjamin Franklin, who famously tied a key to the end of a kite string and flew the kite in a thunderstorm. When sparks leapt from the key, he correctly concluded lightning
is an electrical current.
Kasparian and colleagues, atop New Mexico’s South Baldy Peak during two storms, said they used laser pulses to create filaments of charged gas that conduct electricity akin to Franklin’s kite string. No air-to-ground lightning was triggered because the filaments were too short-lived, the researchers said. But further improvements, they added, could come by reprogramming their lasers with more sophisticated pulse sequences.
Pulsed lasers may be a powerful way to trigger lightning because they can form many so-called plasma filaments, the investigators said. These are channels of ionized, or charged, air molecules that act like conducting wires extending into the cloud.
The idea of using lasers to trigger lightning was first suggested more than 30 years ago, but couldn’t be put in practice before because previous lasers weren’t powerful enough, the scientists said.
Kasparian and colleagues involved in the Teramobile project, an international program initiated by National Center for Scientific Research in France and the German Research Foundation, built a powerful mobile laser capable of generating long plasma channels by firing ultrashort laser pulses.
They tested their device at the Langmuir Laboratory in New Mexico, which is equipped to measure atmospheric electrical discharges. The lab, atop 10,500-foot South Baldy Peak, is in an ideal place because its altitude places it close to the thunderclouds, the group exalained. The researchers said they measured the electrical activity in the clouds after discharging laser pulses, and that statistical analysis showed the pulses indeed enhanced the electrical activity there.
The findings appear in the latest issue of the research journal Optics
Express.
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In what they call a first step toward conveniently triggering artificial lightning, scientists say they have touched off electrical discharges in thunderclouds by shooting powerful lasers at them. “We generated lighting precursors,” said Jérôme Kasparian of the University of Lyon in France, one of the researchers. Creating lightning is an important tool for studying the mechanisms of lightning and testing the lightning resistance of airplanes and infrastructure, added Kasparian and colleagues. Scientists have been able to trigger lightning strikes since the 1970s by shooting small rockets, spooling long wires behind them, into thunderclouds. But only about half these attempts work, said Kasparian and colleagues. Laser technology, they added, would make the process quicker, cheaper and could open up new applications. Lightning still isn’t fully understood, though it been studied since the times of Benjamin Franklin, who famously tied a key to the end of a kite string and flew the kite in a thunderstorm. When sparks leapt from the key, he correctly concluded lightning was an electrical current. Kasparian and colleagues, atop New Mexico’s South Baldy Peak during two storms, said they used laser pulses to create filaments of charged gas that conduct electricity akin to Franklin’s kite string. No air-to-ground lightning was triggered because the filaments were too short-lived, the researchers said. But further improvements, they added, could come by reprogramming their lasers with more sophisticated pulse sequences. Pulsed lasers may be a powerful way to trigger lightning because they can form many so-called plasma filaments, the investigators said. These are channels of ionized, or charged, air molecules that act like conducting wires extending into the cloud. The idea of using lasers to trigger lightning was first suggested more than 30 years ago, but couldn’t be put in practice before because previous lasers weren’t powerful enough, the scientists said. Kasparian and colleagues involved in the Teramobile project, an international program initiated by National Center for Scientific Research in France and the German Research Foundation, built a powerful mobile laser capable of generating long plasma channels by firing ultrashort laser pulses. They tested their laser at the Langmuir Laboratory in New Mexico, which is equipped to measure atmospheric electrical discharges. The lab, atop 10,500-foot South Baldy Peak, is in an ideal place because its altitude places it close to the thunderclouds, the group exalained. The researchers said they measured the electrical activity in the clouds after discharging laser pulses, and that statistical analysis showed the pulses indeed enhanced the electrical activity there.