Fully electric ice thrower

Question

Flamethrower and Icethrowers are common weapons used in my story. I know how a Flamethrower works and I have already implemented the Flamethrower but I am having trouble thinking of how an "ice thrower" could work. So how could an ice thrower work?

• The icethrower should be able to freeze whatever it hits
• The ice thrower should be fully electric however if this is too hard then chemicals can be used
• The setting is about 100 years into the future and nanotechnology exists.
• The ice thrower does not have to be portable
• The ice thrower can use things like water, and air

Edit: The icethrower only has to freeze whatever it hits and what the beam is does not matter as long as it freezes or at least cool down whatever it hits by at least 70 degrees Fahrenheit.

Answer 1

You could make an 'ice thrower', though I am not sure how useful it could be.

Water is a good cooling material. It is common, and has a high specific heat per unit mass. It is good at wetting and cooling, so you don't get the vapour barrier you get with liquid nitrogen.

You can supercool pure water to -48C. This will turn to ice when shocked. You could make something that squirts liquid water that turns to ice when it hits the target. It would turn to ice in flight, but you can perhaps delay this by passing it through a series of fine tubes to create a turbulence-free jet. Fire-fighter's hose nozzles do this, so the water goes further. It may even be possible to supercool the water at the same time, which would be a better solution than carrying tanks of supercooled water that would go solid if they were tapped.

You have not got a flame-thrower with negative energy. It is a Super Soaker, with stuff that turns to ice when it hits. If I was hit by one, I could probably shake off the ice if I was quick and suffer no ill effects. It will be heavy as it carries the water it needs to shoot.

If you want an ice weapon, a sock filled with ice cubes might make a good cosh...

Answer 2

Basics: Cryogen & Physics:

The principle is clear: You need to have a cryogen that is able to freeze the target. The most commonly used one is liquid nitrogen which can reach temperatures of roughly -200°C. -273°C would be absolute zero for our universe.

The problem you have is, that even when using super-cold cryogen, they have to counteract thermo-dynamical processes which add temperature to the coldest spot. Meaning: You cool down a portion and the surrounding matter in normal temperature scales will immediately flow to the cold spot, thus heating it up again.

Liquid nitrogen is not able to do "substantial freezing", except when the target is in an isolated tank or some container. I had some droplets of liquid nitrogen on my hand once during a demonstration of super-conductivity and guess what: nothing happened. My hand did not splinter into pieces.

It probably takes hours for liquid nitrogen to fully deep-freeze a substantial amount of matter.

Possible technical solutions (with a tad of Sci-Fi):

• Portable freeze-thrower (like a flame-thrower): Would probably be very ineffective. It's more like a portable snow cannon. Not that impressive.

• Liquid nitrogen capsules: This weapon would fire shells filled with liquid nitrogen. Avoiding the nitrogen heating up during the flight through the "warm" atmosphere. Upon impact the shell bursts and the nitrogen can do its work. Problem still: It wouldn't insta-freeze the target. It might have stopping power on humans or robots maybe, because of the impact on power systems or just causing confusion and maybe panic.

• Laser cooling: This is a theoretical possibility, working on atomic scale. One advantage is, that it works without a special cryogen. It is considered that you can use lasers to very accurately control the energy states of an atom, so that it loses energy and emits photons. This process can theoretically cool down to absolute zero. Problem: It needs several lasers focused on one very tiny spot. Therefore it would be a bulky machine. Energy hungry. Not realistically plausible, but possibly in a Sci-Fi world. The effectiveness against a target is open to debate. Can be an insta-freeze effect, if you like.

• Bose-Einstein-Condensate: One "cool" solution, very Sci-Fi, very not possible to be built in our current understanding of physics, would be using the ultra-cool BEC-state of a gas or liquid as a cryogen. This one can have any properties you like upon hitting the target. Possibly best combined with the capsule-shell idea.

  Nobody knows how to create a substance in its BEC state (so far it was only produced in atomic scales), so the invention of a machine would be up to you. It has kind of the same touch of "magic" to it as anti-matter has to propulsion and is closely related to quantum mechanics.

Answer 3

A mixed approach might be best with a multi barreled "gun" firing short slugs of highly pressurized liquid machine gun fashion. Some barrels could fire highly chilled fresh water or salt water just above its freezing point to saturate the target. The other barrels could fire liquid diethyl ether chilled down to -110 degrees C. All barrels could be adjusted to focus in on the target depending on range.

Answer 4

Compressed Air

The ice thrower has a very powerful, very fast compressor which captures air and converts it to liquid oxygen. When it's got enough compressed air, you simply aim and decompress toward the thing you want to freeze -- like emptying a regular can of compressed air. It will make stuff cold.

The nanotech will be critical for making a compressor efficient enough for this kind of device. It's well beyond what we are capable of doing today. When it's charging, it will be loud because of all the air it sucks in. The change of state from gas to liquid will generate a lot of heat, so your nanobots have to cycle out and fly around above the device to cool themselves. The faster you want this to happen, the more nanobots you'll need to have flying around up above. To make it a useful weapon, you may need the cooling bots to make for several times the mass of the solid-device in operation below them.

When you discharge the device, it will get very cold, and you'll need to cycle out cold nanobots for hot ones. The nanobots have to cycle out both ways. When it's charging, there will be a large heat-wave in the air where the nanobots are cooling themselves. When it's discharging, there will be condensation around the device, possibly showing as a cloud.

The design of the nanobots will have to be specially geared for compression; they need to be able to link into one another strongly and sustain extremely high pressures as a group. Take some inspiration from nature. Trees generate very high negative pressures in their capillaries; I'm sure there's something out there that generates very high positive pressures.

It will take a lot of air to get a reasonable charge to do what you want it to do, so the longer you let the device work, the more realistic it will seem.

Answer 5

I like the idea of using the electricity to rob the target of whatever heat it has.

I'm just gonna think outloud on that bit alone.

Idea 1) It's almost like how we use lasers to cool down a handful of cesium atoms to do research on them. The thing is they're in a very very controlled container where the atoms are being shined on from 6 directions just below the absorption frequency, so a Doppler effect takes place if the atom is moving towards a laser, absorbs it, and slows down. I don't know what 100 years from now looks like but you would have to figure out what your target is made of and throw photons at it with just the right wavelength at specific atoms, haha. But it would only be coming from one direction, not 6. So you would only rob a portion of the atom's velocity.

I'm limiting myself here but just to consider using electricity alone to affect regular matter is a limitation, because everything is more or less electrically neutral given that atoms balance their positives out with negatives. And you can't really change that because then you'd be changing the chemistry of your target and turning them into goo or exploding them wouldn't really be a freeze ray.

Idea 2) A grenade might work if your nanobots came out and slowed down the energetic atoms, kind of like a Maxwell's demon approach. They would rob the surface of whatever they landed on of heat. They would have to do something with that energy like converting it to light and shining it away. Which might be a really cool effect, a huge flash of light and the thing is frozen. Then I guess they would have to self destruct to make the area safe again. But that's not really an ice thrower, either.

Sci-fi idea) The problem is really the way heat works. It's all vibrations of molecules and you have to slow them all down. In order to do that you have to take their motion and put it somewhere else or convert it to another kind of energy. Grabbing their heat is the hard part. It's really sci-fi and out there but if you had a molecular tractor beam and your device was able to transfer that molecular jiggling to your gun, your gun could then get rid of the energy any way it wanted. Maybe the gun forces the atoms into a grid, and all their vibrational energy is transferred to the emitter then.

Here's my last idea and I'll stop, lol) Nanotech exists, right? So that means we must have gotten pretty good with chemical engineering and chemistry and getting things exactly the way we want them. What if we shot a liquid, much like the flamethrower's fuel, but the liquid has an extremely endothermic reaction with oxygen or nitrogen or water, or whatever is available in your world, something common. Chemistry isn't my strong suit so I'll leave it up to smarter people than me to figure that out but it's basically the mirror image of a flamethrower. You have an exothermic reaction with the air in that case, why not an endothermic reaction? That way it would be basically the same thing, just different fuel.