"Lightning gun" discussion

[JDP12]

I was intrigued by Fnord's thread regarding future possibilities for launchers. Especially by the idea of a lightning gun- or more specifically, basically using a water gun with a conductive solution to conduct electricity.

I don't have a huge background in electricity, but this seems like it could be an interesting idea to pursue. The basic idea is that you would shoot a conductive solution (saline probably?)

So I'd like to begin a discussion on this idea, in the hope of building one eventually.

My basic idea right now is a type of water gun, could easily be adapted from any dozens of designs out there, firing a saline solution. There would be some source of high voltage- probably a stun gun, since it delivers constant pulses, and not one single pulse.

I'm thinking of using a standard stun gun to deliver the pulse, but was wondering about using multiple stun guns. Possibly wiring them in series or parallel? It's late at night, I can't remember which would be a good idea.

Soo time for questions.

1) What would be the optimal solution of salt in water?

2) Would it be best to wire stun guns in voltage or parallel? I can't remember which one is better... pretty tired.

3) Is there a way to calculate how well the current will transmit through the water? I assume some MAY be lost due to air, but it should follow the path of least resistance which would be through the water stream. So is there a way to calculate voltage delivered, taking distance and such into account? Could you treat it similar to a wire, using the resistance of the solution? Obviously as you get really far away, current may be lost since of the water starting to "bead" apart at the end of the stream.

Input is greatly appreciated, as this could be a very interesting project to pursue. Thanks!

[Technician1002]

Unless you deliver parallel streams of water the risk is high that you and the ground you stand on will become the return path for the current. There is a reason the police tasers us two wires.

[JDP12]

ah. That makes sense. So using two streams of water, that makes sense. Thoughts on my other questions?

Thanks for the advice.

[clemsonguy1125]

Mythbusters tried this a while back except they used water. What I remember besides it didn't work is it can not be a pump gun. The air pressure separates the water in droplets. You need a stream or water.

[JDP12]

yea. That makes sense..

So a plunger system may be the best setup here? I believe that would give a solid stream, although the range is extremely limited. You may need something to "drive" the plunger.

[clemsonguy1125]

Best design I've seen is where air pressure forces the pison forward like a plunger.

[saefroch]

1) What would be the optimal solution of salt in water?

The higher the concentration, the better. I wouldn't worry about using an inactive electrolyte to so much, just avoid halides. The higher the concentration, the better the conductivity.

2) Would it be best to wire stun guns in voltage or parallel? I can't remember which one is better... pretty tired.

Wiring in series will increase voltage, but in parallel will decrease voltage and increase current. I suggest series, because the higher the voltage, the lower the current, and the lower the energy dissipated in a resistor, by P= I²R. Just be aware, you're going to absolutely fry whatever electrolyte stream you're using, and cause all sorts of electrochemical reactions.

[starman]

Water streams of any type are not going to be practical and even potentially dangerous to the shooter.

Work on building this:

[youtube][/youtube]

..and I think you'll have something...

[saefroch]

At but still there we have the issue of directing the current... can you suggest a viable alternative to water solutions?

[Skywalker]

Check this out: conducting fibers, plasma, and ionizing laser beams instead of water:
http://www.newscientist.com/article/dn6014

[Fnord]

You'll have problems with water, as everyone else has said. I know a decent amount about the electronics/physics involved, and although it is possible, such a device is probably as much a threat to the user as it is the target. But there's a more serious flaw that I don't like about your idea; you don't get to see things catch on fire or blow up.

Stun guns, even a bunch in parallel, are still fairly low-energy devices. What I was considering in the future alternatives thread would be an anti-material pulse weapon which could probably be handheld, so figure maybe a 2 kiloJoule discharge at most.
The most I've ever dead-shorted by hand was 300J(equivalent of about 50 camera capacitors) and it is kinda scary. 2kJ is enough to explode small objects if they are conductive enough. You can barely catch paper on fire with a stungun.

I may try this in the future, as an effective projectile-less energy 'weapon' is a personal holy grail for me, but for right now I just have to wait until solid-state laser tech catches up to my needs

[saefroch]

Well since the topic has been mentioned, does anyone here have knowledge of solid state lasers above what's mentioned in the sadly small wikipedia article, like what media are often used, and what level of efficiency is achievable?

I've heard of YAG lasers used somewhere before (probably in materials research or ceramics) but I have no idea where...
EDIT: Found it, part of my father's PhD thesis.

Back to the main topic, on lightning guns you'd have to have a very large capacitor bank, but I think a device styled somewhat like a stun gun would work if you could hook them up in series. After all, it's almost impossible to put a large hole in something with any sort of hobbyist-level man-made electrical discharge, and stun guns have proven more than effective at what is undoubtedly very low current. A lightning gun wouldn't be intended to destroy anything, but it could wreak havoc on any sensitive device that uses current, electrical fields, or electrical imbalances.

[Technician1002]

For the water streams to be unbroken, laminar flow nozzles should be considered. Laminar flow also conducts light.

[youtube][/youtube]

[JDP12]

Wow thats pretty cool. After a bit of googling, it seems like a big concept is slowing down the flow... This causes it to be in an arc, effectively destroying any range of potential use in this. Can you speed it up and still maintain the laminar effect?

I realize this would probably never make an effective "weapon", but it is a cool experiment that could be interesting in its ability to short things out.

[saefroch]

That laminar flow reminds me of the video below, which does not use laminar flow, but still demonstrates the ability to "conduct" light. [youtube][/youtube]
I'd say just experiment with laminar flow nozzles, there's probably some way to make a stable jet of water, though the fluid dynamics of why the water stream breaks up is probably beyond me, and certainly beyond my education thus far.