If China figured out Fusion first, would they keep secret how to do it or is scientific knowledge like this shared?
It makes no sense for them to hide it; they're going to be singing from the rooftops that they were first if they achieve that.
It'd be like if we went to the moon, but kept it under wraps. Like, why bother?
If China were close to a surplus-energy generating Tokamak, the smart thing to do would be vague about it while pumping out a lot of disinformation to confuse Western intelligence agencies about the most productive path forward for research.
1) Get geopolitical dominance by showing you have it first (while still trying to prevent theft of IP)
2) Use it in quiet and in low usage to decrease vulnerability to state actors from stealing the tech.
One more important thing. Hiding it only hides it from other governments' populations, not the foreign governments. Because of this, most countries go for option #1.
EDIT: If it needs further clarification, this is the French model of fission plant buildout.
Just imagine a scenario where Chinese GDP doubles over 5 years, while greenhouse gas emissions drop to zero over that same period. Imagine China's glee and their cackling laughter as Westerners scratch their heads wondering why.
For the record, I am an American who reads about plasma physics in my free time, under the distant hope that I can help America win this race.
Not to mention the geopolitical advantage they would get deploying fusion plants to Africa, etc.
Much of the point of space programs is to prove we can drop bombs back on earth with precision. I don't know how fusion reactors are a threat in that fashion.
During the space race and Cold War, Russia and the US used surveillance to determine each other's weapons capability & capacity (and still do). There's no need for the space program to remind the enemy of what they already know.
The space program was a pissing contest, effectively, and while there was surely some military undertones, the point of our space programs was not as a deterrent - it was a show of might.
I do in fact doubt this. We've been building fusion weapons for 50 years very successfully, progress in fusion power plants is negligible in comparison. If fusion power plants are a dual use technology for weapons, they must be a very inefficient way to get there.
Other players will rush to get the solution in their hands, by all means at all cost.
To put it in perspective, the US is fighting china over relatively mundane nonsense like 5G, semiconductors, etc. Fusion would be many orders of magnitude more important than any tech we have today.
The US exploited the control of oil to conquer and rule over the entire world. Every nation on earth is a vassal on some level ( even china and russia ) to the US because we discovered and exploited oil first and pretty much ended up controlling most of it around the world. The international world order is an american world order because of oil. If madagascar or north korea discovered fusion, they would control the commanding heights and they wouldn't share such a secret without getting something in return. If that is the case for madagascar/north korea, major nations like china, japan, france, germany, russia, india, turkey, nigeria, brazil, venezuela, etc who don't want to be under american domination would be even more incentivized to keep it for themselves.
What is the value of limitless free and environmentally friendly energy? Priceless. It's the type of tech which alters human trajectory and the world order. Not only is fusion priceless in and of itself, it's priceless in terms of it's derivative effects. Discovery of fusion can lead to general AI and vice versa.
In other words, ain't nobody sharing fusion tech - at least not without significant strings attached.
If you are still unconvinced, go look up oil production before and during ww2. Before and during ww2, the US produced more oil than the rest of the world combined. And after ww2, with control over saudi/OPEC oil, venezuelan oil, canadian oil, etc, we controlled the world's oil supply.
The bountiful oil reserves within our borders and the early exploitation of it is why the US became the world's dominant power. Oil is why ww1 and ww2 was fought. Oil is why we won ww2. Oil is why we won the cold war. Oil is why the american international world order exists.
As you noted, oil isn't a form of energy, it's a weapon. Take away the power of that weapon and there's not telling what would happen.
Best of times. Worst of time.
But of course no one has solved the neutron damage issue. How could they? To develop a material, if that's even possible, that could withstand 14 MeV neutrons well enough, one would need a fusion reactor to make those neutrons to test the materials (and tritium breeding to keep it running). This circular dependency would be very difficult to traverse.
Research tends to be so international these days that the chances of any country keeping significant breakthroughs to themselves are pretty slim. Scientists from countless nations are working on ITER and pooling their knowledge.
The only way to keep these things under wraps is if you were running it as some kind of top secret project from the start and poured billions into it. And then you'd still be operating at a disadvantage because you can't bring in outside expertise. Considering the scale needed for serious Tokamaks (and not just small research models) and also the history of the field, I have a hard time imagining a scenario where such a thing would be kept under wraps.
Fusion research is really an international community. There's not much "they" to point your finger at.
Free(ish) energy is the kind of thing that fundamentally rebalances the global order. US control of shipping lanes, or consistent access to oil is what has made the US the super power it is. China inventing Fusion would make all of that obsolete.
By the time all the agreements with China to respect IP are in place, China will be producing more patents annually than any other country.