Lightning and lasers

[steve-o]

Check out Globalspec CR4 thread "electricity from lightning" We had a pretty good time talking about that very subject.

http://cr4.globalspec.com/thread/2701

[buffo]

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.

Um... Capacitors don't store AC, they pass it. They store DC. So you'd need a big, honkin' capacitor to capture the DC of the lightning and one hell of a big inverter to make AC if you wanted to power a substation. (I can't even begin to imagine the dielectrics involved... After all, the bolt just traveled through a thousand feet of air! What are we going to use to top that?)

Still, there *is* a crapload of power available in lightning, if only we could harness it. ("channel it... into the flux capacitor!" no, wait - wrong movie...) I read that it strikes the surface of the earth an average of 10 times each second. Of course, the surface of the earth is a pretty large area, but lightning is a lot more common in some areas than in others. (The clock tower in Hill Valley being a prime example.)

When you ship large capacitors the terminals should be shorted to avoid building up a lethal charge.

Just make sure the thing is completely discharged (through a suitable resistive load) before you hook up the shorting device, or else you'll end up welding said device to the capacitor! Scarry things, large capacitors....

Maybe another good story for Mythbusters to play with.

Would probably make for some great TV!

Adam

[steve-o]

Lets contact them and see if they'll do it. They're just about crazy enough to try something like this!!

[buffo]

You know, it would make for a very cool episode. They'd probably go to that indoor lab that has the lighning simulator again. (The one they used to test the myth of whether a tongue piercing will increase your chances of getting struck by lightning...) I can just see them rigging up some big-ass capacitor bank and then having one of the caps blow up from overload. (Cue Adam Savage's cackling laugh in 3... 2... 1...)

Adam

[steve-o]

Har!

[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.

Um... Capacitors don't store AC, they pass it. They store DC. So you'd need a big, honkin' capacitor to capture the DC of the lightning and one hell of a big inverter to make AC if you wanted to power a substation. (I can't even begin to imagine the dielectrics involved... After all, the bolt just traveled through a thousand feet of air! What are we going to use to top that?)

Still, there *is* a crapload of power available in lightning, if only we could harness it. ("channel it... into the flux capacitor!" no, wait - wrong movie...) I read that it strikes the surface of the earth an average of 10 times each second. Of course, the surface of the earth is a pretty large area, but lightning is a lot more common in some areas than in others. (The clock tower in Hill Valley being a prime example.)

When you ship large capacitors the terminals should be shorted to avoid building up a lethal charge.

Just make sure the thing is completely discharged (through a suitable resistive load) before you hook up the shorting device, or else you'll end up welding said device to the capacitor! Scarry things, large capacitors....

Maybe another good story for Mythbusters to play with.

Would probably make for some great TV!

Adam

Adam,

I realize capacitors filter AC and store DC voltage but did you know that high voltage capacitors used in pulsed lasers are rated on the speed at which they accept and release a very large charge and are sometimes called AC caps, hence the term I used to describe them.
Those AC or pulse caps I've sold and used in a range around from 10,000 to 75,000 VDC and 6 uF. Hell I've seen tiny super caps at 5 volts but rated at 2 Farads that would stop your heart If the discharge path was right. Even those disposable cameras with built in flashes can have lethal effects since the caps store a large charge and the output from the high voltage pulse transformers can bite you bad.
A friend of mine was sitting in his car one day (parked fortunately) and for some reason decided to dismantle one of those disposable cameras with flash. He got such a nasty shock that he involutarily dropped the cigarette from his lip and before you know it he burnt his crotch with the same fag whose smoke was previously tickling his nose. That was a double whammy !
But god was it funny..... ha ha ha.....

[buffo]

I realize capacitors filter AC and store DC voltage but did you know that high voltage capacitors used in pulsed lasers are rated on the speed at which they accept and release a very large charge and are sometimes called AC caps, hence the term I used to describe them.

Yes, I did. However, it was your comment about connecting them to a substation and powering a community that led me to believe you actually thought they stored AC. (In my defense, I actually *have* meet people that, when they saw the term "AC capacitor", immediately thought, "Cool! I didn't know they could store AC...")

My apologies for insulting your intelligence. ops: I really should have known better; based on your previous posts it should have been obvious that you weren't that naive. (I actually wondered for a moment if you might have been pulling my leg with that part of your post.) But like I said, omitting the inverter step was the clincher. Anyway - sorry!

Those AC or pulse caps I've sold and used in a range around from 10,000 to 75,000 VDC and 6 uF.

Been making coil guns, have you? I've thought about building a railgun myself, but I'm too busy with laser projects to even think about starting another hobby. (Plus I have to admit that I'm a big chicken when it comes to high voltage...)

Even those disposable cameras with built in flashes can have lethal effects

There was a website I was browsing not long ago where a guy took apart several *hundred* of those damn cameras to get the capacitors out of them. Made one hell of a large capacitor bank with them. They're not really rated for the extreme duty of a coil gun, but since they're basically free the guy figured what the hell... But yeah, they can bite pretty hard.

A friend of mine was sitting in his car one day (parked fortunately) and for some reason decided to dismantle one of those disposable cameras with flash. He got such a nasty shock that he involutarily dropped the cigarette from his lip and before you know it he burnt his crotch with the same fag whose smoke was previously tickling his nose.

Damn, that is funny! (That'll teach him to smoke while he's messing around with electronics!)

Seriously though, a high voltage shock can really cause damage. Which is one of the reasons I'm so afraid of it. (Been nailed a few times - enough to know how bad it hurts at least... Flyback transformer, neon sign transformer, geiger-counter/scaler power supply, that sort of thing.) Haven't lost control of my bladder yet, but I've know people that have (momentarily, not permanently) after getting bit...

Adam

[Spec]

Seriously though, a high voltage shock can really cause damage. Which is one of the reasons I'm so afraid of it. (Been nailed a few times - enough to know how bad it hurts at least... Flyback transformer, neon sign transformer, geiger-counter/scaler power supply, that sort of thing.) Haven't lost control of my bladder yet, but I've know people that have (momentarily, not permanently) after getting bit...

Flyback... Weak. Neon sign transformer... Now were talking.

I took a hit from my tesla coil a long time ago, I still have the marks on my right hand to prove it.

Couple microwave oven transformers in a voltage tripler setup, 12kv, *certified* unhealthy amperage.



I think this gives a good explanation as to why I'm not too terribly bothered by HV circuit tinkering... After one hit from this thing everything else that bites feels a little pedestrian and lacking.

[LaserLover]

Hey guys here's a nice portable laser that could be used to discharge lightning by Ionizing the atmosphere. And it's only about 4 hours drive away in the next province of Quebec, Canada, EH !
Check this out " http://newsroom.spie.org/x5329.xml "

Yeah, I played with tesla coils, voltage triplers, millions of volts, sparks and arcs and survived.
Although I think Conan the Barbarian might react aversively after a few hits. What doesn't kill you the first time ???? Doesn't necessarily make you stronger. Hopefully a bit wiser.
I wonder how many one eye laser scientists are still around ?

Rick

[DZ]

Since we are talking about high voltages and currents; as we all know, when you dump a massive amount of current into a coil you create an intense magnetic field, briefly, so what can be done with this magnetic field you may ask. Well, how about shrink coins! http://205.243.100.155/frames/shrinkergallery.html

David