Why do you think that no state put significant effort into fusion research? You would imagine the first country to figure it out would dominate the world for decades to come.
Could you give some sources for that or explaing where exactly the problems in fusion technology lie and how it could be solved by throwing money at it?
ITER is planned to be completed in 2026 and it'll generate a net 0 of electricity at 300MW in/out.
It seems the issue with fusion is that it actually works much better at scale. But the same could be said about nuclear reactors - it obviously is much harder to build a compact one.
Does it work better at scale? The sun definitely produces a lot of energy in total. However, "the Sun's "power density" is "approximately 276.5 W/m3, a value that more nearly approximates that of reptile metabolism or a compost pile than of a thermonuclear bomb".
If, overlooking the details, we were able to build a cubic meter sized "fusion box" that outputs 276W, then it would take about 2 million of them to produce a reasonable output for a power plant of 600MW. And it would take up about half the volume of NASA's vehicle assembly building, ignoring any support structure needed. That's not unimaginably huge, but it's pretty large compared to other types of power plants, I would think.
So assuming we solve all the technical problems to capturing the power source of the stars using handwavium or perhaps generously donated alien widgets, I wonder if it might still be uneconomic.
