Field-reversed configuration simulations using the full two-fluid plasma model

Abstract

Summary form only given. Simulations of field-reversed configurations (FRC) are presented within the full two-fluid plasma model. The model takes into account electron inertia effects, charge separation and the full electromagnetic field equations and allows for electron and ion demagnetization. Two-fluid models are particularly suited to FRC simulations as typical FRC separatrix radii are on the order of the ion-gyroradius, at which spatial scales two fluid effect become dominant. The simulations were performed using a shock-capturing finite-volume algorithm, based on the solution of Riemann problems at cell interfaces. The study is divided into two parts. In the first, FRC stability is studied. The simulation is initialized with various FRC equilibria and perturbed. The growth rates are calculated and compared with magnetohydrodynamic (MHD) results. It is shown that the FRCs are indeed more stable within the two-fluid model than the MHD model. In the second part formation of FRCs is studied. In this set of simulations a cylindrical column of plasma is initialized with a uniform axial magnetic field. The field is reversed at the walls. Via the process of magnetic reconnection FRC formation is observed. The effects of rotating magnetic field (RMF) drive on the formation of FRC are also presented. Here, a set of current carrying coils apply a RMF at the plasma boundary, causing an electron flow in the R-Z plane leading to field reversal. The strong azimuthal electron flow causes lower-hybrid drift instabilities (LHDI), which can be captured if the ion gyroradius is well resolved. The LHDI is known to be a possible source of anomalous resistivity in many plasma configurations. The study is concluded with a discussion of possible effects of anisotropic stress tensor on FRC equilibrium and formation