Magnetized Target Fusion (MTF)
High-Level Concept: A hybrid approach to fusion, MTF uses a magnetic field to confine a low-density plasma (like an MCF device), while surrounding the plasma with an (often liquid) metal liner. The metal liner is then heated and compressed using inertial-confinement techniques such as lasers, or pistons. While plasma densities are significantly lower than most ICF machines, the theory is that the longer confinement times and better heat retention will allow MTF devices to produce comparable power levels and will be easier to build.
History: The first MTF device was built by the US Naval Research Laboratory (NRL) starting in 1971. It utilized mechanical compression of a solid metal liner, however liner cost and replacement made the reactor impractical and subsequent designs address the problem with spinning molten metal liners. NRL’s Linus program was eventually cancelled due to a variety of engineering challenges. The method was revitalized in 2002 by General Fusion.
Challenges: There are a variety of engineering challenges to overcome including plasma preparation and injection methods, magnetic flux diffusion in the molten liner, removal of vaporized liner material between fusion pulse cycles, axial plasma losses during compressions, and achieving high tolerance piston synchronicity.
Notable Projects: General Fusion, Magneto-Inertial Fusion Technologies, HyperJet Fusion