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Curved Laser Beams Could Help Tame Lightning
Urchin writes "Laser beams just gained a new property — they can curve through space. That's what happens when ultrashort laser pulses pass through a phase pattern mask and a lens, which together shift the most intense region of the beam from the center to the right-hand side. The asymmetry in the pulse causes it to drift progressively further to the right along an arc as it travels. The laser beam is so intense that it ionizes the air it passes through to create a curved plasma channel. Those kinds of channels can be up to 100 meters long — direct them at thunderclouds and they could first trigger lightning to spark and then act as a convenient but short-lived lightning rod to guide it safely to the ground, according to some researchers."
So, this is a neat twist on an older idea.
I can't really imagine a practical use for this (a lightning rod seems like a much cheaper solution) but it's pretty nifty science.
Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
just gained a new property
wait, what? I don't think that's how science works...
What's the value of information that you don't know?
Normally the refractive index of a material is quoted as a constant. However, light radiation will slightly distort the electron levels of the material they are passing through, and this will have effect the refractive index. Normally this effect is very tiny. However, if you design high-power lasers, then it can become a nuisance. If you have a bright spot to your beam, then this will locally raise the refractive index. This will, in turn, cause the light to come to a line focus, which raises the intensity even more. If you do not design high-power optics to account for this, then a flat, uniform beam of light can spontaneously divide into a set of filamentary hot spots, which can smash your expensive optics.
There is another process, more usually associated with high-power ion beams. An ion beam that travels a long distance in air can twist like a garden hose squirting water. The ion beam heats up the air it is passing through, which creates a kind of pipe through the air as the hot atoms move away. This is a nuisance if you want to make the beam go in a straight line. One way of keeping an ion-beam weapon firing straight is to put a laser pre-pulse to heat a straight line through the air for the ion beam to travel down.
Christodoulides's team's work could be combined with his to help aim the laser pulses and plasma channels at specific targets, such as clouds, although he points out that the laser pulses can also be guided using mirrors. "But it would be fun to see curved lightning discharges," he says.
This article is cool up until the lightning bit. As the quote from TFA shows, there's absolutely no connection between the curved lasers and the technique for triggering lighting. As far as generating an ion channel goes, the curved laser does nothing a straight laser can't. The only connection between the otherwise completely disconnected bits of research is that the lightning guy commented on the curved laser stuff and essentially said that while using mirrors is more feasible in his project, using curved lasers would look cool.
Everytime someone comes up with an interesting discovery in science, people invariably ask what it's good for. Ditto for math. The problem is that a lot (most?) research is done for its own sake, to discover new things, rather than having any particular application in mind. History has shown that applications tend to come later, and in the places you least expect it, so it pays to just be curious. People thought group theory was just weird abstract shit until someone figured out how to use it in applied chemistry.
It's said when the need to immediately justify every new discovery has gotten to the point where an article needs to include a completely contrived and ridiculous application just to placate people.