Does electron-electron fusion exist?

I’ve never heard of such thing. Should be similar to hydrogen to helium fusion, but…
Is it all about masses and strong interaction and something - I don’t know.
Should it give less energy with more effort than the other fusion?

No, it doesn’t. If electrons are close enough and not going fast, they will repel each other. If they are close enough and going fast enough to smash into each other, they will still not fuse, but rather form a shower of other particles out of the collision energy. But you still won’t have an electron-electron nucleus.

I am not a particle physicist, but… no. You’re correct that the strong interaction is relevant here–the strong force allows protons and neutrons to “fuse” together into atomic nuclei.

An electron is a lepton particle, and one of the defining characteristics of leptons is that they don’t participate in strong interactions. Therefore, the dominant interaction when you try to bring two electrons closer is an electromagnetic interaction; since they both have negative charges, they’ll repel each other more strongly the closer they are.

Other particles, so this has been done.

It just depends what you mean by fusion. In everyday parlance the word fusion is limited to mean the merging of two atomic nuclei into a different nucleus or nuclei, possibly with some particle emission in the process. In this definition, it doesn’t make sense to talk about anything other than atomic nuclei as being involved in fusion.

In specialized settings, “fusion” can refer to other forms of particle interactions where two things become one or more other things, but this usage is limited to fairly technical settings. It’s never used for electrons.

Having said that, yes, as Ludovic notes electrons can be smashed into one another to make other particles. It is never exothermic and will never happen without net energy input.

You can sort of stably put two electrons together. If you have a broad definition of things.

Take 4 antineutrons. Jam in your two electrons with a couple of antineutrinos into the antuneutrons. Hope, really, really hope you end up with 2 antiprotons and 2 antineutrons. Presto, a stable nucleus of anti-Helium. -2 charge.

Store in a safe place, preferably away from ordinary matter. Not adding 2 positrons helps preserves charge so it can be moved around and suspended.

Why on Earth do you think it should be similar? One is the fusion of baryons, particles made up of quarks, where some of the protons involved change into neutrons, but where you still have the same number of baryons.

What do you think you should get if you “fuse” electrons? They are not made up of quarks, don’t come in “proton” and “neutron” versions, and unlike protons and neutrons they don’t stick together in lumps.

Nuclear fusion and any sort of electron ‘fusion’ are completely unrelated. In the former, the attractive strong force between (the quarks constituting) protons and neutrons can overcome the repulsive electromagnetic force between protons and produce a stable nucleus. Electrons do not participate in the strong interaction (they’re fundamental particles without any color charge), and they don’t form any bound, stable system.

If you’re just talking about a process that looks like e + e + stuff -> other stuff, then sure, that happens all the time and with any other particle.

The point about fusion (and fission) is that the energy contained in the nucleus to hold it together varies slightly from being a linear relationship to the number of nucleons (protons and neutrons) in the nucleus. It turns out that the strong force holding the quarks inside protons and neutrons provides most of the mass, not the quarks themselves. This force also provides the force between protons and neutrons themselves (when it gets called the nuclear force, it is the residual left over outside the proton or neutron.) Anyway, if you measure the mass of a hydrogen nucleus (ie typically a proton) and work your way up, adding protons and neutrons you discover that the mass of each atom is very slightly less than simple addition would suggest, until when you reach iron, you are roughly the mass of an entire proton short of what the count would say you should have. Then the masses start to grow again. This change is mass is the difference in the amount of nuclear force needed to hold the each different number of protons and neutrons together for different atom.

So, if you smash a couple of light nuclei together, and they form a new heavier element (up to iron), there is some binding energy left over. That is what you get out of fusion. Break apart a heavier atom into smaller atoms (done to iron) and you also get energy left over. This is fission.

Electrons are themselves fundamental particles, but they don’t participate in the colour force, and so far as we know, there is no other force that can attract electrons together to overcome the electrical repulsion (like happens to create a nucleus) and again, no mechanism to bind them together in any way, other than to assemble them around something with a positive charge. (Ignoring gravity here, for useful purposes it is far too weak.) Things with positive charge are nuclei - in which case you get an atom, or a positron, in which case you get a very short lived pair called positron. But the electron and proton will annihilate one another in short order. That will yield energy, but it isn’t fusion, and you only get back (at best) the energy it took to make the positron.

The short-lived “atom” consisting of an election and anti-electron (aka positron) is called positronium. Francis Vaughan appears to have wanted to mention it but didn’t fully type out the name.

:smack: I might claim spell-correct - but I think my fingers simply didn’t finish the job. They do that.