Aeronaut wrote: have they any idea how to capture and use all that glorious heat? If so, is that part of the 3.5 to 5G$ already budgeted?
The real purpose of the NIF is to test models for thermonuclear warheads to ensure the reliability of the US nuclear stockpile without actually blowing up the occasional warhead. To do that, you need to be able to produce fusion on a regular basis.
The NIF is emphatically not designed to produce a practical source of fusion energy, or even to provide a path for designing a practical fusion generator. While I have no doubt that very useful information about the basics of the D-T fusion process will come from their research, I think the NIF is being rather misleading to suggest the facility is a major step in the road to practical fusion energy. It’s really a weapons lab that (at some point) happens to produce fusion.
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