Scientists Used Lasers to Curve Electricity Around Solid Objects

“If you are able to guide electrical discharges, you can guide lightning."

Jun 19 2015, 6:55pm

Photos of laser beams from the study: (A and B) Gaussian beam, (C and D) Bessel beam, and (E and F) airy beam. Image: Clerici et. al

We live in a world where diverting lightning strikes with the help of lasers is already more or less a reality. With that insanely sci-fi concept in the can, researchers have begun getting down to the nitty-gritty: telling it where to go.

"If you are able to guide electrical discharges, you can guide lightning and it can go, for instance, where you can collect the energy of the lightning," said Matteo Clerici, the lead author of a new study released today in Science Advances that could help scientists do just that.

Clerici is part of a group at Institut National de la Recherche Scientifique in Quebec that has been experimenting with techniques for controlling electricity and say they have developed a way to use lasers to channel electricity along curved arcs and around solid objects.

They start first by inducing electrical breakdown between two electrodes, creating a surge of electricity with an erratic and unpredictable trajectory, much like lightning. They then use a laser beam to create a path of less-dense, ionized air, which becomes the course of least resistance on which the electrical discharge naturally tends to travel.

While this basic concept of directing electricity had already been proven, Clerici and the other members of the team have now shown that they are able to make it do more than move in a straight line.

"Our point was not all the lasers propagate on a straight line," Clerici said. "Some have an intensity peak that moves on a trajectory of a parabola and the idea was to move these lasers to guide the discharges along a curved path."

By applying this basic technique using specialized lasers like the "Bessel beam"—a type of laser with unique properties including a curved trajectory—the researchers were able to create directed, curved arcs of electrical discharge. In other words, the researchers have found a way to literally bend electricity to their will.

The researchers also found that they were able to use these new techniques to get the arc around solid obstacles placed between two electrodes. Another characteristic of the "Bessel beam" and the "Airy beam"—another curved-trajectory laser the researchers used in experiments—is that they are "self-healing." This, the report explained, means that if "even if the main intensity peak is blocked while the remaining part of the beam is allowed to pass, self-healing takes place and the intense part of the beam reconstructs itself after encountering an obstacle," which allows the electrical discharge following the beam to continue.

Caption from the paper: Effect of an obstacle placed in the control beam path. (A), (C), and (E) show how the intense part of the beam (the blue fluorescence in the photographs) is modified upon the insertion of an object in the beam path for a Gaussian, a Bessel, and an Airy beam, respectively. In the Gaussian case, the intensity of the beam is completely quenched after the obstacle and there is no way to guide an electric discharge between the two poles shown in (B). (D and F) In contrast, for both the cases of a Besseltype and of an Airy-type propagation, the beam restores itself after the obstacle and the electric discharge occurs along an almost unaffected trajectory. The inset in (D) shows a multishot acquisition where the discharge in the region right after the obstacle chooses different paths for different shots, before converging to a straight trajectory when selfhealing takes place.

These two lasers have also proven significantly less erratic than those used in previous studies. According to the research article, in "the case where a standard Gaussian beam [a commonly used laser beam] guides" the discharge, "the arc trail is heavily distorted and effectively unpredictable," whereas these two new beams are "guided along a much better defined path, with no evidence of random jumps."

Clerici said this new, more precise technique could have numerous practical applications outside of weather control and electrical safety. On the scale that the INRS team was working on—just millimeters—Clerici said their techniques could be used for welding and and cutting micromachinery with an incredible degree of accuracy.

However, Clerici added that this phase of their research is mostly just "proof of concept," and that the group is looking to see what else they can do with near-total control over a force of nature.

"What we've show is that a laser, especially a Bessel beam, can allow us to direct an arc along a set path," Clerici said. "Now we want to see what we can do with that; we're next going to try to move it along an L-shape."

If all goes according to plan, that means they'll soon be able to use the awesome power of Zeus himself to spell out "LOL." Amazing, isn't it?