Fusion Reactor Studies are performed for a variety of purposes, p.e.: to learn about the properties of later fusion reactors, to obtain guidance for the fusion R&D programme, or, as in the case of ITER, to design and construct an Engineering Test Reactor. It is selfunderstood that the conclusions reached in each of these cases will rest on the input assumptions made. These input assumptions are purpose oriented and may show considerable differences between each other. The range will go from assuming rather large margins applied to the data base in order to be on the safe side for the reactor to work, to assuming rather large improvement factors above the state of the art in order to reflect a learning curve. All these cases are individually justified provided one keeps in mind the purpose of the work and the corresponding nature of the assumptions. Difficulties occur when comparing the conclusions of different approaches without going back to the assumptions.This paper extracts from the various reactor studies the relation between the assumptions made and the results obtained, and then aims at drawing some general conclusions. It mainly discusses tokamaks but some comparison is also made with stellarators and reversed field pinches.
Engineering design conditions and constraints affecting experimental fusion reactors and power-reactors