[pastullo]

The idea of having many small fusion reactors is quite interesting. I never thought about it and i would normally dismiss it since building a big one is cheaper than building many little ones. However, SpaceX and their 9-engine Falcon rocket teach us a different story. Sometimes building smaller yet complicated power plants is cheaper than building fewer ones but bigger.

Would be great to know more about the economics behind a multi reactor power plant.

[gmueckl]

The real issue is surface to volune ratio of the contained plasma. This needs to be as small as possible for the containment to be effective (reduced energy losses through the surface area). So you want your reactors to be as big as possible.

[pfdietz]

From an engineering point of view, though, you want the reactor to be as small as possible. That's because output is limited by the power/area that the first wall can withstand. So, the volumetric power density will be inversely proportional to the linear dimensions of the reactor.