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Pulsed terawatt lasers have surprising effects when shone through the air (2006)
- saidajigumi 10y agoThis, while quite interesting, also feels like a member of a nascent genre: "XKCD What-If? citation trolling."
- daveloyall 10y agoIn case you missed it: Take a close look at the last photo, the one near the text "control of lightning strikes".
- rdtsc 10y ago> using pulsed lasers to trigger and guide high-voltage discharges over several meters in the laboratory. There is no way the military have seen that and haven't thought "I bet we can use that to fry our enemies"
- aaron-santos 10y agoI love the idea of generating two parallel beams and leveraging the conductivity of plasma as a sort of "wireless" taser. It's likely not feasible (I'm guessing someone has tried it), and it would be interesting to know why.
- street 10y agoI suspect being hit by the beams might harm the victim, with the electricity just being a bonus. I doubt the laser generators are cheap and portable as well.
- rdtsc 10y agoIt has an EMP potential to fry electronics probably.
- kragen 10y agoIt's called an "electrolaser": https://en.wikipedia.org/wiki/Electrolaser https://en.wikipedia.org/wiki/Electrolaser. There are reports that they work in practice, but not yet well enough for use. I don't know why.
- dmitrygr 10y agoThe laser power might kill the victim, but using this for actually sending electricity might work. Might be a good replacement for high power lines in some cases.
- noobermin 10y agoLast year, I attended a colloquium from a scientist from the army weapons' division specifically about this (filaments). He kept extolling the career opportunities available at his lab...doing weapons research. I will be (if the funding comes in, fingers crossed) funded by the DoD too...and what I am doing is laser plasma related but it isn't directly weapons research.
- tbrownaw 10y agoThe kerr effect sounds interesting, even if it is air-only... what power density would it take to get self-focusing in a vacuum by gravitational lensing?
- aexaey 10y ago> what power density would it take to get self-focusing in a vacuum by gravitational lensing? Not this is a question I'd look forward to be answered by Randall Munroe in his http://what-if.xkcd.com/ http://what-if.xkcd.com/
- dzdt 10y agoYes. Send it!
- davidhowlett 10y agoSent, I would love to see Randall Munroe's take on it.
- kragen 10y agoThe Kerr effect is present in many different transparent media, but not in vacuum. You're probably right that sufficient power density would give rise to self-focusing by gravitational lensing, but it seems like the necessary power density would be very high — the gravitational acceleration needs to be a substantial fraction of c very frequently, like 0.001c over every interval where diffraction gives you a divergence of one milliradian. A narrower beam moves the escaping light you need to capture closer to the center of mass of the beam, but also increases that divergence. It isn't obvious to me how to calculate this. Can anyone help?
- spott 10y agoYou likely couldn't get gravitational lensing, you would probably get pair production first, which would screw with your energy density.
- reallydontask 10y agoI spent countless hours of my PhD trying to get the White light continuum stable enough to do measurements with. Our laser wasn't powerful enough to use air as medium, so we would use sapphire (very good, stable and predictable), Calcium Fluoride (absolutely bloody terrible, but it did give out a lot more UV light) and water (never got any measurements out of that, so unstable)
- dmitrygr 10y agoMost interesting thing in the article: they can likely use pulsed lasers to guide lightning!
- sametmax 10y agoNow the next question: does the laser consume more energy than the lightning bring ? Because maybe we can use that to harness energy in storms.
- qb45 10y agoThe big problem is building batteries that could absorb some buttload-Joules of energy in a fraction of a second. IIRC some researchers tried (just with metal rods instead of lasers) and all they got was expensive fireworks.
- sametmax 10y agoWell, maybe you could redirect the current directly into the grid and spread it accross it so that the power is divided accross the entire network and save fuel from power factories in the process. If you can predict the hits, you can balance the production accordingly.
- 0xffff2 10y agoYou would certainly want capacitors rather than batteries to do the initial energy capture. That doesn't really help much though; the amount of energy in lighting is of a completely different scale from what we can handle with current technology.
- kbob 10y agoHow about using the energy to heat/boil water?
- ChuckMcM 10y agoTwo words: Graphene Capacitors :-)
- tbrownaw 10y agoThat is, hiking the peak power of the laser pulses that are applied increases the number of filaments that result without notably influencing the individual intensity or the energy each filament carries. So these filaments are basically quantized particles? ...and their pulse length of 70 femtoseconds would be about 0.02 mm, or not too far off how wide the filaments are. I guess the proportions would be similar to a pair of saucers with the rims stuck together.
- genericone 10y ago"... back-directed light is the result of partial self-reflection of the forward-traveling beam..." "the idea of using a high-intensity laser to ionize air along the beam, thus forming a conducting channel of plasma" Real life light sabers are within the realm of possibility with existing technologies!