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# What does a small fusion reaction sound like?

5 days ago

I am familar with current reactor (experimental) fusion reactor design.

But imagine a fusion reaction happening without a reactor, so there is no reactor hull to shield the sound from an innocent bystander.

It is a small reaction and it is continuus and controlled. (so not all reactive matter is consumed at once)

Would it make a sound at all?

If yes, what would that be?

In Sci-Fi shows and the like you will very often here humming and zapping sounds and so on, resembling electricity. Would that be the case?

Please do not consider how realistic such an occurence would be or what happens to the energy 'gained'. I have taken care of that part already :)

The device I am talking about is a sort of beam emitter.

Input: Matter in form of small metal spheres.

Output: a "energy beam" of variable width and intensity.

The most plausible reaction to explain that (magical) behaviour is a fusion reaction, at least that

• How close have you ever stood to an operational nuclear reactor? I've been within about 20 feet of at least two different ones. It sounds like boring, heavy piles of shielding and maybe you sort of hear the coolant pumps through the hull. If you want to get into the physics, I can do that, but to keep it light hearted, the saying is 'hot rock make boat go'. Fission reactions literally come down to a fancy metal plate that gets hot when you put it close enough to other fancy metal plates at just exactly the right geometry.

Fusion doesn't just happen naturally anywhere except in a star, but that's pretty much just because nature didn't find a better way on its own. We have the opportunity to shove hydrogen into a magnetic bottle and pummel it with particle beams until it gives us its lunch money. As long as the hydrogen is close enough to itself when it goes kerflooey, it could keep going kerflooey. There's some really boring math here, but the jist of it is that the reaction has to

5 days ago
• I imagine it'd sound a lot like the sun or a star would, but it wouldn't necessarily be extremely loud.

Most sound comes not from the fusion reaction, the fission reactions, burning coal, or whatever the source of energy is, but the equipment that is being used to gather the power being produced. And the sounds those make vary widely depending on application. A coal-fired power plant is going to make a lot of noise because there's no need to spend the extra effort in making it quiet, while a ballistic missile submarine is designed to be almost perfectly silent when it has to, while still generating plenty of power to do its job.

5 days ago
• I would challenge your continuous operation specification. Many things that we humans think of as continuous are in fact just oscillating really really fast. You think that light is "on" when it is actually fluctuating 50-60 times per second.

Your fusion reaction is likely to be operating like the light, fluctuating cyclically very quickly and only appears to be continuous to a human.

When things cycle quickly like this they tend to make a sound, anywhere from a low hum to a very high pitched whine depending on the frequency. These sounds are very commonly associated with electrical equipment which commonly cycle in similar ways. This is what your fusion reaction would sound like.

It is of course entirely possible that this sound would be swamped by the sounds of associated equipment in the area. You couldn't hear the sound of the reaction over the sound of the giant coolant pumps, the sparking of power supplies, or the blast of the ventilation system.

5 days ago
• It is hard to answer the question while ignoring the energy gained issue, as some of that gained energy will likely express itself as vibrations which human ears would interpret as sound. Beyond this small portion of the yielded energy which directly becomes sound, most of the rest would interact with surrounding matter in ways that could indirectly create large volumes of additional noise.

If by "I have taken care of that part already", you mean that all of the energy being released by the fusion is being funneled off for some other use, then the noise generated by the reaction would either be a side effect of that funneling or the result of inefficiencies in that funneling process.

Postulations on what those funneling sounds might sound like, would require more information on how the funneling occurs and in what form the energy is funneled away.

5 days ago
• So you're firing a fusion type reaction in a beam?

Let's ignore the science and use some creative use of the 'known knowns'.

A fusion reaction, such as the ITER Tokamak project, involves isolating a plasma in a magnetic field. Now you've specifically requested you remove the 'housing', which would then remove the magnetic field... which leaves us with plasma.

Plasma itself is just matter in the '4th' state... beyond turning into a 'gas', matter turns into a plasma when it reaches a high enough energy state to shed it's electrons and therefore it ionizes. The device or weapon you need would likely absorb, utilize or otherwise discharge the electrons as 'waste' and would be firing the ionized material as the projectile.

So perhaps you don't really require 'fusion', as such, but a device that perhaps uses fusion to heat other pieces of matter (such as the metal spheres (although it doesn't have to be metal)) to incredibly high temperatures and then shoots them in a particular direct

5 days ago
• Probably the same sound as a bare fission reaction would make.

You only hear that which is registered by the temporal lobes in the brain. Usually those are receiving input from the auditory nerves, which are usually only excited when the tympanic membrane is vibrated by sound waves carried across molecules.

So, in the roughest manner, sound is perceived when longitudinal waves of energy travel through media — such as the air, the ground, your body, and the like — and vibrate your eardrums.

Nuclear fusion occurs when the distinct nuclei of two or more atoms approach near enough that it becomes easier for some of their neutrons and protons to fall into mutual nuclear “orbitals”. ‘Orbitals’ are, of course, a slightly antiquated name for the set of energy states which are considered to be stable for a certain set of conditions: why electrons stay near an atom, and why the nucleus of that same atom stays intact.

There are a few, and not too many, ways we know this could happen.

5 days ago