Two-Fluid Simulations of Field Reversed Configurations
Author: Ammar H Hakim
Requested Type: Consider for Invited
Submitted: 2006-12-18 12:46:18
Co-authors: P. Stoltz, S. Kruger
Contact Info:
Tech-X Corporation
5621, Arapahoe Avenue, Suite A
Boulder, Colorado 80303
USA
Abstract Text:
Fluid models of plasmas are a common tool to study fusion devices. In this work algorithms for the solution of Two-Fluid plasma equations are presented and applied to the study of Field Reversed Configurations (FRCs). The Two-Fluid model is more general than the often used magnetohydrodynamic (MHD) model. The model takes into account electron inertia, charge separation and the full electromagnetic field equations and allows for separate electron and ion motion. Finite Lamor Radii effects are taken into account by self consistently evolving the anisotropic pressure tensor equations. A detailed study of FRC stability and formation is performed. 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 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 a 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.
Characterization: E5,E6
Comments:
