Flashing into view

By | Science & Technology
Lightning strikes in a largely unpredicatable pattern. Might high-powered lasers allow scientists to control this natural phenomenon? Credit@Kim Seng

Researchers at the INRS (Institut national de la recherche scientifique) in Canada may have unearthed a way to guide electrical discharges using laser beams and even steer them around obstacles. The breakthrough was published late last week in Science Advances and shows how electricity may be bent with lasers using a technique based on an unusual principle of physics.

Lightning often flashes throughout the sky in a largely unpredictable pattern, even though lightning rods may be used to influence its strike location somewhat. At a much smaller scale, discharges between two electrodes are very similar to lightning, striking through space creating electric arcs with fixed start and end points. Professor Roberto Morandotti and his team may have devised a method to guide the path of electric discharges.

Researchers from the INRS reawakened a subject that was of intensive research in the 1970s. Electric arcs have been used extensively in combustion engines, pollution control technology, lighting and machining. The ability to control the path these electric arcs take may open up a wide new range of applications; the new research aims to spark creativity in scientists.

Recent scientific advances, as well as Professor Morandotti’s team demonstrated how electrical charges typically follow a smooth path along a straight or parabolic trajectory. Experimental figures from the research article display how various types of lasers may influence a discharge’s properties and trajectories in unique ways. The team even achieved an S-shaped trajectory by using multiple beams.

Credit@Ted Fu

Credit@Ted Fu

Professor Morandotti aimed to understand whether the self-healing properties of certain shapes of laser beams (for example Airy and Bessel beams) might be useful in his experiments to control electricity. Lasers with this characteristic were used because a beam whose intensity peak is impeded by an object may rebuild itself once clear. In other words, if the centre of the beam is obstructed while the rest of the beam continues around the barrier, the laser beam may continue forward with a reconstructed core. As electricity races from one electrode to the other, its path is typically variable and unpredictable, which creates sparks. However, the team was able to demonstrate that when an object was placed between two electrodes, lasers may guide the electric arc around the object without touching it and return to the laser on the other side.

“What we’ve shown is that a laser, especially a Bessel beam, [may] allow us to direct an arc along a set path. Now we want to see what we [might] do with that; we’re next going to try to move it along an L-shape,” Matteo Clerici of the INRS in Quebec and lead author of an article announcing the new technique said.

The potential to influence lightning might mean harnessing its power for a number of productive applications. Credit@Kim Seng

The potential to influence lightning might mean harnessing its power for a number of productive applications. Credit@Kim Seng

“Our fascination with lightning and electric arcs aside, this scientific discovery holds out significant potential and [seems to open] up new fields of research,” said Yves Bégin, vice dean of research and academic affairs at INRS. “This spectacular proof of concept, which was conducted over a distance of a few centimetres, required the high-power lasers, state-of-the-art facilities, and extraordinary research environment that our professors helped to create at INRS. Being able to work in such cutting-edge labs enables our students and postdoctoral fellows to embark on the path of scientific discovery even while still in school.”

The lasers used in the experiment require car-sized power sources to heat and electrically charge the air. Doing so clears a path for the electric arc by freeing electrons from air particles and allowing current to flow. Regardless, it might be the first step in harnessing lightning from nature, protecting populated areas from strikes, jamming electronic signals and perhaps collecting the electrical energy to provide energy.

What other weather patterns might be unexpectedly controllable in the future?

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