Between 35 and 40 years ago I did a term paper and oral presentation on hot fusion for a high school class in ... I forget which subject; not sure what grade it was, either. Certainly it was *at* *least* 35 years ago.
Conclusions that I drew: -- Laser fusion would be possible, *but* the only lasers powerful enough at the time were neodymium glass lasers, and they had several problems: They were expensive, they were very inefficient, and the glass cracked after a relatively short working life. Consequently it was hard to see how the process could ever be made practical -- or even over-unity -- unless far, far better lasers were developed. -- Magnetic confinement fusion had proved much harder than anyone expected, due to the fact that super-hot plasma in a magnetic field acts like a very badly behaved fluid. It develops peculiar "instabilities" when it's hot and under pressure, which result in its wiggling out of confinement and touching the container walls, at which time it cools off instantly and that's the end of the reaction. It's kind of odd that almost four decades later, the same exact oral report could be given over again with almost no changes. Oh, there've been some improvements in laser technology; they've finally gotten better materials than neodymium glass, I think. But the basic problem -- too little beam power at too high cost and too low efficiency -- hasn't changed. And magnetic pinch, zeta pinch, stellerator, and so on designs have evolved into the Tokomak and variations, which can contain the plasma longer and and under more pressure -- but the fundamental problem, which is that magnetic "bottles" leak like Klein bottles, remains the same. When God builds a nuclear reactor he uses brute force. Humans are trying to use cleverness to get the same result with a lot less force, and it does seem rather like the basic problems are kind of fundamental...
