> A proper hydrogen bomb would be purely fusion. But a fission device is used to get the fusion reaction going in all practical designs, I think. The fine art

> A proper hydrogen bomb would be purely fusion. But a fission device is used to get the fusion reaction going in all practical designs, I think. The fine article describes the design of the US's actual hydrogen bombs as follows - I don't know if you'd count them as 'proper': > So there are really three stages of nuclear reaction in such a bomb: the primary (fission), the secondary’s internal fuel (fusion), and the secondary’s casing (more fission).