Since the 18th century, mankind has had a fairly effective means of combating lightning – a lightning rod. It performs a simple task – so to speak, during a storm to attract the attention of lightning so that it does not strike a nearby building, antenna, mast or other structure, but rather a metal rod driven into the ground.

In general, the lightning rod performs its function very well, but either out of curiosity or boredom, scientists decided to invent a method more suitable for the 21st century. And what could be more technological and futuristic than lasers.

How does the new lightning removal method work?

laser lightning removal idea, beam filamentation (the propagation of a light beam in a medium without diffraction). As it propagates through the atmosphere, a sufficiently strong beam becomes self-focused. Self-focus is accompanied by an increase in density, the great value of which ionizes the air.

Free electrons scatter the beam, so it travels some distance under conditions of dynamic competition between these two effects. As a result, a long narrow plasma channel is formed in the air, which has high conductivity for milliseconds and therefore attracts lightning.

Sentis Tower is 124 meters high and is located two and a half kilometers above sea level. This is a very popular object among physicists who study lightning. The thing is, lightning hits him on average. a hundred times a year.

Sentis Tower photo with long exposure to show the laser beam / Photo arxiv

The group of scientists who prepared the study placed a laser at its base and directed the beam almost parallel to the tower. It was a laser that emits a thousand picosecond pulses in one second at a wavelength of 1030 nanometers and an energy of 500 millijoules (Yb:YAG laser).

Based on laboratory work, the physicists adjusted the setup in such a way that, filament It started almost immediately near the lightning rod end of the tower and reached at least 30 meters above.

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Measurements show that 84 percent of the lightning striking the Sentis Tower over a 9-year period was negative (ie, the negative charge was effectively transferred to the ground), 11 percent was positive, and 5 percent was bipolar.

However, all four laser-induced lightning bolts were positive. Only in one case was the sky clear enough to videotape the discharge from the two observation points. The recording shows that a broken lightning bolt follows the laser beam 50 meters. It also has no branches, unlike ordinary lightning bolts.

Image from video: controlled lightning from above, ordinary from below / Photo arxiv

During the experiment, the authors concluded that the key to success was the high repetition rate of laser pulses.

During filamentation, a small fraction of free electrons generated by ionization in a strong laser field are captured by neutral oxygen molecules. At a high laser repetition rate, these long-lived charged oxygen molecules accumulate and preserve the memory of the laser path at a low separation energy, which facilitates the propagation of the discharge.

In addition, physicists made calculations that confirmed that, under the created conditions, positive lightning would require a smaller electric field than negative lightning. And although the results can not yet be called a working laser lightning rod, the scientists proved its fundamental possibility, and also indicated the optimization aspect of this process.