This is the
technology of producing a fusion reaction in a controlled manner.
(As opposed to the uncontrolled
Fusion Explosives).
Such control necessitates some way of confining very hot and very
energetic material without using up its energy. This technology
does NOT necessarily mean that this process is net energy
productive. It might well not be. Fusion for energy
production is in Fusion Power.
Since Fusion Explosives do not depend on the
containment of the fusion reaction, this technology is essentially on a
separate development track, and is only weakly linked to it.
In the real world, this technology is partially
complete (fusion can be controlled for several milliseconds), but
cannot be continued long-term.