This results in free protons flying all over.

As a result, the hydrogen remains in the solution as a free proton.

In the vast majority of these cases, it is not really a free proton, but instead is surrounded by solvent molecules.

Two hydrogen-3 nuclei can then fuse into helium-4 plus two free protons.

A free proton or neutron does not disappear.

First, producing free protons to work with is not easy.

At sufficiently low temperatures, free protons will bind to electrons.

The spontaneous decay of free protons has never been observed, and the proton is therefore considered a stable particle.

For free protons, this process does not occur spontaneously but only when energy is supplied.

Additional hydrogen is constantly being heated to produce free protons, which, when hot enough, also fuse to maintain that power.