Lasers beams have been used for the first time to trigger and divert lightning bolts. It was first postulated in the 1990s that lasers could be used to create a low-resistance pathway through the atmosphere, allowing lightning bolts to use the path of least resistance.
Terawatt lasers, that could pulse for femtoseconds, were eventually created making this a possibility. The pulses were so intense that they rip electrons from air molecules, forming a channel of ionized air along the path of the beams. These paths focused the beams into high-intensity zones called filaments, keeping the air ionized long after the laser beam had passed through. However, this technique failed to trigger or direct lightning.
Researchers, led by André Mysyrowicz of the applied optics laboratory at ENSTA ParisTech in France, were able to direct lightning using a filament path. In another experiment, the laser beam was able to pass 5 to 20 cm (2.4 to 7.9 in) from a lightning-producing electrode and an oppositely charged electrode. The beam was generated 50m (164 ft) away. Usually, lightning will jump from electrode to electrode, but when the laser was on, the discharge jumped to the laser filament and followed it. The researchers published their findings in the journal AIP Advances.
Applying this outside the lab will prove challenging, as clouds don’t have electrodes that can be touched and distances are vaster. However, with a more powerful laser, they might be able to develop precise specifically-shaped pulses to guide lightning through the air.
Reference: “Triggering, guiding and deviation of long air spark discharges with femtosecond laser filament” by B. Forestier, A. Houard, I. Revel, M. Durand, Y. B. André, B. Prade, A. Jarnac, J. Carbonnel, M. Le Nevé, J. C. de Miscault, B. Esmiller, D. Chapuis and A. Mysyrowicz, 17 February 2012, AIP Advances.
DOI: 10.1063/1.3690961
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