Back when I was in high school almost fifty years ago, I attended a talk about fusion power. The speaker explained how fusion reactors worked differently than fission reactors, and used only water as fuel instead of highly radioactive uranium or plutonium. He spent a good bit of time on the difficulties standing in the way of commercial power generation with nuclear fusion reactors, and dwelled on how hard it was to keep a thin, extremely hot gas (plasma, really) from wriggling around and extinguishing itself on the chamber walls.