What are the limits of fusion in modern times? How much better is it than fission?
Achieving fusion on Earth is very difficult because you need to squeeze nuclei together very hard before the strong force kicks in and you get a bound state (see some of the above questions), and you have to do it in a safe and controllable way. Here’s one link I found with info: http://fusedweb.pppl.gov/. There are a couple of different approaches: one is “magnetic confinement”, in which magnetic fields are used to try to keep the hot particles squeezed together. Another approach is “inertial confinement”, which employs high-intensity laser beams blasting a deuterium-tritium target. My impression is that although people working on this are making slow but steady progress, fusion as a practical means of energy generation is a fair ways away. From the point of view of energy generation, fusion of H isotopes has the potential to release more energy per mass of fuel than fission. But there is an enormous host of practical matters that complicate things, and so far, it’s been possible
