I don’t know if stellarators have a different plan, but in a production tokamak, it’s a combination of:

- deuterium-tritium fusion, which produces lots of high-energy neutrons

- the neutrons help to keep the plasma hot, but being neutral, they escape the magnetic bottle; there is a lithium blanket around the reactor to catch them

- the neutrons that hit the lithium produce tritium for the reactor, and steam for the turbines