Lightning strikes flow along laser's path for tens of meters:
Lightning rods protect buildings by providing a low-resistance path for charges to flow between the clouds and the ground. But they only work if lightning finds that path first. The actual strike is chaotic, and there's never a guarantee that the processes that initiate it will happen close enough to the lightning rod to ensure that things will work as intended.
A team of European researchers decided they didn't like that randomness and managed to direct a few lightning strikes safely into a telecom tower located on top of a Swiss mountain. Their secret? Lasers, which were used to create a path of charged ions to smooth the path to the lightning rod.
The basic challenge with directing lightning bolts is that the atmospheric events that create charged particles occur at significant altitudes relative to lightning rods. This allows lightning to find paths to the ground that don't involve the lightning rod. People have successfully created a connection between the two by using small rockets to shoot conductive cables to the heights where the charges were. But using this regularly would eventually require a lot of rockets and leave the surroundings draped in cables.
The idea of using lasers to guide lightning is an old one, with the suggestion first appearing in the scientific literature back in the 1970s. A sufficiently high-intensity laser beam has a complicated relationship with the air it travels through. The changes it makes to the air help focus the laser, while the electrons it knocks loose tend to disperse it. Meanwhile, the molecules in the atmosphere that absorb the light heat up and shoot out of its path, creating a low-pressure path in the laser's wake. Critically, many of the particles left behind in these low-pressure filaments are charged, providing a potential path for lightning.
It's also possible to shape laser pulses so that you control where the generation of these filaments start—up to a kilometer away from the laser source.
[...] Aside from the frequency, the tower is a great site for these experiments since it is equipped to study lightning. Instruments measure the current that flows through its lightning rod and the electromagnetic fields in the area and can perform imaging at various wavelengths, including X-rays.
In any case, the researchers thought this time might be different for a key reason: Lasers have improved considerably. They're now able to fire much more rapidly; the one set up for this work is capable of a 1 kilohertz frequency. That is a firing rate over 100 times larger than any laser used for this sort of work previously. Models that include this rapid cycling, the researchers show, suggest it creates a more persistent filament of charged particles in the air.
And it worked. Over six hours of testing, the tower saw four strikes while the laser was active. Imaging of one of these, which occurred in a clear sky, clearly shows the lightning bolt moving along the path defined by the laser until it reached the tower.
Like almost all the lightning strikes previously recorded at the Säntis Tower, all four strikes started at the ground and propagated upward. But 85 percent of the strikes recorded there involve a connection to a pool of negative charges in the clouds. By contrast, all four laser-guided strikes connected to a positively charged pool.
Journal Reference:
Houard, Aurélien, Walch, Pierre, Produit, Thomas, et al. Laser-guided lightning [open], Nature Photonics (DOI: 10.1038/s41566-022-01139-z)
(Score: 3, Interesting) by Mojibake Tengu on Thursday January 19 2023, @01:51PM (8 children)
What if sufficiently strong laser may discharge the lower layers of the ionosphere to the ground?
Such lightning strike could burn out wipe whole cities, without any possible technical remedy...
Respect Authorities. Know your social status. Woke responsibly.
(Score: 1, Funny) by Anonymous Coward on Thursday January 19 2023, @02:20PM (5 children)
You really are a glass half-empty personality type, aren't you?
(Score: 2) by Freeman on Thursday January 19 2023, @03:11PM
Just because you're paranoid, doesn't mean they aren't out to get you.
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 2) by Mojibake Tengu on Thursday January 19 2023, @03:28PM (1 child)
It's been done in prehistory already, several times. Recorded in myths.
And my life credo actually is: You are never paranoid enough!
Respect Authorities. Know your social status. Woke responsibly.
(Score: 1, Funny) by Anonymous Coward on Thursday January 19 2023, @06:23PM
I always worry that I'm not insecure enough.
(Score: 3, Interesting) by aafcac on Thursday January 19 2023, @08:03PM (1 child)
The problem is that it only takes one catastrophic mistake to end life as we know it. I remember before they spun up the LHC, there was a nonzero chance that it would create a black hole obviously it was a low probability and didn't happen, but it wouldn't have stopped it from killing everybody, including those not involved.
(Score: 2) by hendrikboom on Friday January 20 2023, @03:32PM
There was *fear* that a back hole might be created in a collision. Not realistic. Collisions more intense than the LHS's collisions happen every day in the atmosphere from cosmic rays. The function of the LHC is simply to have some happen where thy can be studied.
(Score: 2) by Reziac on Friday January 20 2023, @03:36AM
Well, that's a cheerful thought...
Many moons ago I lived on a flat rural plain in a high-thunderstorm area with ground water only a few feet below the surface. There was a shallow pit about 200 feet from my house that got hit repeatedly during every storm, sometimes rapidfire. (Meanwhile, I never observed a hit on the big radio tower across the road.) Mind you this was close enough to see the lightning's width, which is a durn scary sight at that range.
Best guess around the neighborhood was that someone had buried a car there (the sunken spot was about the right size) but no one was willing to so much as walk across the spot to find out, never mind dig a hole...
And there is no Alkibiades to come back and save us from ourselves.
(Score: 2) by corey on Friday January 20 2023, @11:12AM
Yeah, but I didn’t think lasers (light) was an ionising radiation. Maybe it is if it’s intense enough? A directed beam of X-rays on the other hand…
(Score: 1, Interesting) by Anonymous Coward on Friday January 20 2023, @03:34AM
Does it count as pointing a laser at an aircraft if it's a laser lightning rod and an aircraft flies past the beam?
https://www.faa.gov/about/initiatives/lasers/law_enforcement_guidance [faa.gov]
What you probably would want to do is to adjust the collimation so the laser "lightning rod" won't blind pilots and other stuff beyond a certain range.