The more I read about fusion, the less I think it's anything near to a star. The kind of fusion is completely different. A sun wouldn't work on earth because it doesn't produce enough energy per square meter. It isn't even in de same ballpark. The only reason why our sun produces so much energy is because it's so incomprehensibly large. A compost heap produces more heat per square meter than the sun.
Fusion reactors are incredibly cool. But they're not "harnessing the power of a sun".