Planned diagnostic suite of the MTF Fusion Demonstration Plant

General Fusion is developing an integrated spherical tokamak MTF prototype called the Fusion Demonstration Plant (FDP) at the UKAEA Culham Campus. Diagnostic observation of key plasma properties during compression will allow General Fusion to advance physics predictions involved in this fusion concept in a path toward a power plant.

The compression system consists of a cylindrical wall of rotating liquid Li that is driven inward by an array of pistons in a way that creates concavity to the inner surface as it compresses the enclosed plasma to a volume ~1000x smaller. Diagnostic access during compression becomes difficult as view ports are occluded and the plasma inhabits a smaller space. Magnetic pressure during late stages of plasma compression is on the order of a gigapascal and thus limits the options for diagnostic placement.

Diagnostics to constrain the plasma equilibrium include Mirnov coils, Faraday rotation polarimetery, Thomson scattering LIDAR, and interferometry. Temperature will be measured with ion Doppler, neutron Doppler, TS LIDAR, and bremsstrahlung from x-ray photodiode ratios. Neutron yield will be measured with scintillators and activation counting materials. Radiated power will be measured with bolometery. Elemental composition will be determined using optical and x-ray survey spectrometry.

The surface trajectory and shape of the liquid metal liner will also be measured optically in order to constrain the plasma boundary and understand plasma-wall interactions.