Lightning and lasers

[steve-o]

This guy aimed his laser pointer across a lightning storm and got some really cool photos. (WL forum) I mentioned though that it may not be a good idea to aim a laser into a lightning storm due to path ionization and he might get struck! I know this is true for nitrogen lasers, but does anyone know about a >200mw 532mn DPSS?

[buffo]

You're not going to ionize air with a 200 mw DPSS laser. Maybe a kilowatt CO2 laser, but not any DPSS model

[steve-o]

Well, I wasn't thinking of just ionization--maybe other beam properties..

[buffo]

No worries about the laser beam attracting lighting. Seriously, there isn't any property of the beam that is going to make it more likely that you'll get struck. (Unless we're talking about *kilowatts* of power, in which case you might get some ionization of the air in the beam path that could increase the conductivity enough to provoke a strike.)

However, if you are outside in a thunderstorm, you are already taking a risk - laser or no laser.

And, just to cover the bases - if you are hell-bent on provoking a lightning strike, and you are CERTAIN that you can protect yourself against electrocution, you can indeed cause lightning to strike by launching a small model rocket that trails a very thin conductive wire behind it into a thundercloud.

You don't have to use anything fancy - a simple Estes brand single-stage rocket with a C or D size engine should work just fine. The trailing wire should be as fine as possible (think 36 gauge or higher), and loosely coiled in huge-diameter loops on the ground. When the rocket reaches 1000 ft or so, you'll get a strike if the cloud cover over the launch site is sufficiently charged.

There have been several TV specials detailing this procedure, and I'm sure a quick google search will turn up more information. However, it should be noted that lightning is dangerous as hell, and intentionally provoking a strike can be deadly. You don't want to be anywhere near this rig when you launch the rocket.

Adam

[steve-o]

Adam, yes Ive had this discussion on another forum about the rocket with the wire etc.
I was just needing info on which lasers create a channel in the atmosphere
Thanks
Steve

[jkaiser3000]

I think I read somewhere that UV lasers, with enough power, can ionize the air to induce a path for lightning. However, I don't know the wavelength used, most have been fairly short

[chad]

A quick google search on "laser lightning path"

http://www.google.com/search?hl=en&l...th&btnG=Search

Turns up lots of stuff.

Chad

[buffo]

Adam, yes Ive had this discussion on another forum about the rocket with the wire etc.
I was just needing info on which lasers create a channel in the atmosphere

Short duration (10's of nanoseconds per pulse) high power, UV lasers. If you follow some of the links in the google search that Chad posted, you can read a whole bunch about it.

But if you do the math, you'll see that the lasers involved are pretty incredible. (Let's see, 1Kjoule divided by 50 nanoseconds = 1000J/.00000005sec = 20 trillion watts peak power!)

So, again, no worries about ever being able to do this in your backyard. (Unless Bill Gates is your uncle, that is.)

Adam

[steve-o]

Interesting stuff. The N2 laser was what I'd heard of. Ahhh if Bill Gates was my uncle (well I think cousin would be closer--I'm 51...Yeah I could have all kinds of laser toys to play with..A 20 Watt YAG, 30Watt Argon, a helicopter, a boat.....

[LaserLover]

Imagine if you could dump and store those lightning discharges into a massive AC capacitor and harness that amount of energy. Hook it up to your own substation and light up your community.
I wonder how big and thick the dielectric insulators and storage plates would have to be and if it's feasible.
I heard an urban legend about some university in the USA that built a small scale model of the "Ark of the Covenant" through which God spoke to Moses ( basically a honking capacitor used as an acoustic speaker for God).
I heard they were forced to destroy it because it was too dangerous.
When you ship large capacitors the terminals should be shorted to avoid building up a lethal charge. Try simply dropping one to the floor and see that it will take on a charge or leave it on a bench where lots of dry air blows by it all day.
Maybe another good story for Mythbusters to play with.

Rick