Well, there's "beam" fusion, where you send only high energy particles into target that they fuse with. The issue here is getting the beam up to speed in the fi

Well, there's "beam" fusion, where you send only high energy particles into target that they fuse with. The issue here is getting the beam up to speed in the first place. What's especially nice about thermonuclear fusion is that it's feasible that the fusion reaction itself keeps the plasma hot enough. > this means the vast majority of collisions will just send your ions pinging out of the magnetic bottle they are in Here's the thing: collisions get less frequent the higher in energy you go. This seems counter-intuitive, but consider that the vast majority of "collisions" are actually weak Coulomb interactions at a large distance. If you're approaching an ion at very high speed, your trajectory is not deflected very much.