Equilibrium Reconstruction of Beam Driven C-2W Plasmas

In TAE Technologies' current experimental device, C-2W (also called ``Norm'') [1], record-breaking, advanced beam-driven field reversed configuration (FRC) plasmas are produced and sustained in steady-state utilizing variable energy neutral beams, advanced divertors, end bias electrodes, and an active plasma control system. An axisymmetric 2-D interpretative equilibrium code with Kinetic fast ions is developed to infer the internal magnetic field configuration from experimental measurement including the radial profile of density and temperature at the midplane, and the axial profile of magnetic field along the wall. Ampere’s law is solved with actual magnetic field coils, C-2W geometry, and realistic neutral beam sources. An objective function, consisting of comparison between experimental and simulated magnetic fields, is minimized by varying the fast ion sink term until a steady state solution is achieved. The final steady state solution provides a plasma equilibrium with a significant fast ion population. The steady state equilibrium can be used further to estimate the electric field, total energy, and hence for power balance analysis in the new high-confinement operating regime.

[1] H. Gota et al., Nucl. Fusion \textbf{61}, 106039 (2021).