Simulation of FRC Equilibrium and Global Stability

A Field-Reversed Configuration (FRC) is a high beta self-organized plasma where the current which closes the field lines is carried by the plasma itself. The shape and position of the closed field line region is determined by the external magnetic field pressure and by the profile of plasma pressure inside the separatrix and in the scrape-off layer. The internal plasma pressure profiles affect the stability of the plasma to global (low order) modes. Three external actuators which also affect the global stability of FRCs include the external magnetic coils, neutral-beam injection which creates a population of fast ions, and concentric electrode biasing. We use optimization techniques to fit an FRC equilibrium code to the experimental diagnostics of typical C-2W discharges. We use the generalized Ohm’s law hybrid PIC code, FPIC, to study the global stability of the resulting FRC equilibria, subject to the three external actuators. The results are used to assist with interpretation of C-2W experimental results. The simulations were performed at ALCF using computer time provided by the 2018 INCITE program.