How useful would a electricity-over-water gun be?

Question

As water guns today can send a jet of water quite a distance away, I wonder how useful would a gun be, that sends an electric current over a jet of water to its target?

By useful I mean:

1. Gotta be able to replace/complement standard small arms, in terms of range, firepower, others. I'm actually looking to have my protagonist be surprised by the devastation that this thing ought to wreck.
2. Gotta be safe for the user. Some of the bad guys will get fried while testing it, but eventually I want it to be an evil horror weapon of the future, so safety first.
3. Gonna need a cool name. All I got right now is hydralectrogun, suggestions for something better are most welcome :-)

I'm no expert on electricity but I realize that the hydralectrogun will be limited by the power output (power source), and by the range (water jet stability, delivery of the electric charge).

Whatdoyousay?

Answer 1

It will be less useful, more destructive, or less portable than you'd expect.

Firstly: Range. One of the big problems with water as a projectile is that it doesn't like sticking together when moving through the air. The easiest way to see this is to pour a bucket of water off the top of a tall building, you'll see that it very quickly disperses into a series of drops, rather than one cohesive lump. The reason for this is that the turbulence caused by the air rushing past the water is enough to break the surface tension of the water, except for small droplets. For your gun to have any decent range, it's going to have to push that water out fast, and as you're spraying it fast the leading edge of the stream is going to break into thousands of water droplets, rather than one cohesive stream. Why is this a problem?

Electricity doesn't jump as easily as you might think. While part of the stream might be capable of transmitting a current, most of the beam is going to be made of small droplets. From the point of view of the electrical current that's pretty much the same as a lot of air. You can get around this by pumping up the current voltage (Thanks Michael) enough for it to bridge from one drop to the next, but at that point it will also have enough oomph to bridge down all the other drops that are spraying down towards the ground (thanks to the aforementioned turbulence) and ground far short of the target. Or possibly to wrap back around to the operator and ground through him.

We can fix this by spraying more water to keep the stream continuous, but then we reach a different problem: Volume. The further you want an uninterrupted beam of water, the more water you have to push through at a high enough velocity to hit the target. This (sadly) means we have to spray water at an awfully high rate for an awfully long time, which equates to an awful lot of water. It goes from the portable to needing a van quite quickly...

The biggest problem, however, is establishing a potential difference to actually make the electricity flow. You can't set up a circuit through the gun because you'd need two (non touching) streams of water. You can't ground the power, because that would need your gun to be at potential the entire time, which is a very good way for your operator to get zapped and not a good way to deliver a life threatening jolt of power (without the aforementioned operator zappage).

Finally: Water is a great conductor of electricity. So much so in fact that if your enemy gets wet (because you just shot him with a water gun) most of the electricity would likely route down him and hit the ground without causing any damage whatsoever. And really, who wants a dread weapon that can be defeated with a pac-a-mac?

All things considered: You'd be better off with a Taser strapped to the bottom of a super soaker. The super soaker doesn't actually do anything useful, but at least it looks cool.

Answer 2

Not useful at all.

http://mythbustersresults.com/water-stun-gun

Myth busted.

Update because some people don't like answers that short.

If you have ever seen a stream of water under a strobe light, you see that what appears to be a continuous stream is actually a lot of separate droplets. That means that the electricity would have to travel many air gaps, which it does not do well. In practical terms, what appears like it should work would not work at all.

The Myth Busters team tried building a water-stream stun gun, and could not get one to work. It was not until they put 1 million Volts of electricity behind the gun that they managed to get it to work. However, a Tesla coil capable of generating 1 million Volts is not portable and would be impractical.

Answer 3

Why use water?

Water is messy, short ranged, and would have a high chance of electrocuting the shooter.
If you're close enough to use a water gun, you might as well just use a taser and be done with it.

Instead of water, use an ionizing laser beam to create a plasma channel, and send the electricity down that.

This is real world, present/near future technology that's being developed by DARPA, and will probably be available on the battlefields in the next decade.

Answer 4

Mythbusters did it: Mythbusters Water Stun Gun

In short:

• You need a continuous, "laminar" stream of water. The electricity won't reliably arc through droplets at voltages that will stun but not kill. That meant the only production water pistol that worked was the largest one, one of the big syringe-type guns you use in swimming pools.
• You need two streams, one for each side of the circuit. The earth isn't very electrically conductive; you need thousands of watts of power to reliably stream electricity using the actual "ground" as part of the circuit. That means the rig the Mythbusters came up with required two impractically large water cannons.
• You need salt water. Potable drinking water like you get from your sink is actually a fairly poor conductor of electricity; its main shock hazard is that in small amounts it removes air gaps and increases surface area contact between you and a voltage source (and the salt on your skin will make a small amount of water more saline). To get electricity to actually flow through water, you need an isotonic (roughly body chemistry) or hypertonic (seawater) saline solution.
• Distance is still a factor. Wires are used in modern tasers because the resistance over the 20-30 feet of wire is negligible. Even with electrically-conductive salt water, voltage is inversely proportional to the square of distance; at normal taser range, what you get through a stream of water from an ordinary taser is not enough to disable a human, and upping the voltage at the source makes it dangerous at closer ranges.
• Any leak in the device, or even wet hands, and the shooter is in greater danger than the target.

Answer 5

So, this could be a possibility in the future as energy emission technology continues to develop. MIT has a plasma cannon. Japan has a laser that pulses in the petawatts. Energy shields are right around the corner as well. Electricity on its own has a real hard time bridging gaps between conductors because air has a ridiculously high Ohm rating. Like, stupid high. If your conduction medium isn't stable in its shape like water from a squirt gun, you're going to have angry water for a few feet maybe and then plain old water after that as the electrical energy disperses into the air through the air's resistance. To change this, fire the water under VERY high pressure. I mean HIGH pressure. Like well beyond what current materials can handle. You'll get basically ice 7. Which is an amazing conductor of electricity. Better than silver and silver is as close to a perfect conductor as we can get at the planet surface. 0.000015 Ohms. That's not much resistance. What also happens at that pressure is a vacuum forms around the projectile as it travels. The vacuum has no electrical resistance. Electrons can freely bounce around from one atom to the next with no problem. If you understand physics, you know where this is going. Get that pressure just right with an electrical charge, you've made a plasma gun. Hydrogen is the easiest substance to make plasma with. Comparatively low starting temperature, plenty available, goes through multiple phases of fusion during its phases as plasma before becoming helium. Basically, is you shot heavy water at something (H²O²) with enough pressure and an electrical charge, plasma bolt that you'll also get some heinous radiation from. Actually, don't do any of that. Bad idea.

Answer 6

I don't know if this is helpful or not but the weapon would be better used in a non-lethal ship to ship capacity. Water is actually a poor conductor of electricity. It is the impurities in the water that make it conduct. Sea water would be a much better conductor and a ship could just have a hose in the water and one pointed at the target. As mentioned, the flow would have to be laminar, but with a nuclear powered warship at you disposal, maybe something could be done. You'd have to want to make it uncomfortable or possibly lethal for people on the other ship, but I'm not certain why you wouldn't just shoot them with bullets, you know the old way.

Also, you might consider some kind of futuristic coagulant that starts out low viscosity, so it flows through the gun and plumbing at greater velocity and then sort of adheres once it's airborne to hold the stream together. Just a thought.

Answer 7

If a water gun had enough potency in order to the water jets achieve very high pressure it could cause serious injures and damage.

Just think about that the weight and the water currents from floods can distroy houses and small buildings as if they were made of paper.

Answer 8

I know it’s been a while since this question was asked, but here is a link I think is relevant to the OP’s question. Liquid charge stun guns exist that can fire two parallel streams of a conductive water/salt or other mixture. This would be similar to the device the OP was talking about.

https://electronics.howstuffworks.com/gadgets/other-gadgets/stun-gun6.htm

Another suggestion I have for the OP, that would have a similar effect, without using electricity, would be some sort of metal squirt gun flamethrower. Could be a pretty powerful weapon that would inflict the surprised reaction you were talking about.