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Nonlinear evolution of the tilting instability in a field-reversed configuration (FRC) is investigated by means of a three-dimensional full magnetohydrodynamic simulation. Three types of plasma model are considered, i.e., case (a) where the plasma is confined by a uniform external field, case (b) where the plasma is confined by a mirror external field, and case (c) where the plasma rotates around the major axis. For the prolate FRC the internal tilt mode cannot stay at a low amplitude but keeps growing irrespective of whether the mirror field exists or not. When the initial configuration is substantially deformed, the instability triggers an external mode at the plasma–vacuum boundary because of the pressure imbalance. The outgoing flow driven by the external mode tears the plasma into two pieces, and the torn pieces move away toward the axial edges. The growth time is nearly equal to the transit time for the Alfvén wave to propagate over the plasma length. When the plasma is driven to spin with the Mach number of M=1.5, the growth rate is halved compared to the nonrotating case. The spin stabilization is expected to be complete for M>2.5. It is also found that the oblate FRC plasma is linearly unstable against the external tilt mode. [ABSTRACT FROM AUTHOR]

Simulation of the kinetic Alfvén wave is performed using a two-and-one-half-dimensional (2 (1)/(2) -D) macroscale particle [magnetohydrodynamic (MHD) scale kinetic] simulation code. An oscillating antenna current is applied in one of the boundary regions to launch MHD perturbations into an inhomogeneous plasma in which a sheared magnetic field is present. It is shown that the applied perturbation is mode converted into the kinetic Alfvén wave at the Alfvén resonance layers, resulting in resonant heating of both the ions and electrons. When the plasma beta is relatively low, only the electrons are heated along the ambient magnetic field. The electron heating rate is found to be scaled as dTe||/dt∝β1/2e <δB2y>, where βe is the electron beta and <δB2y> is the wave magnetic field intensity. In contrast, ion heating occurs when the ion beta is close to unity and the temperature ratio satisfies Te/Ti>1. Besides plasma heating, it is found that the plasma particles are accelerated along the ambient magnetic field in the direction of the wave propagation through Landau resonance with the kinetic Alfvén wave. [ABSTRACT FROM AUTHOR]

Based on theoretical and computational considerations, it is confirmed that magnetic reconnection driven nonlinearly by a kink instability plays a key role in the magnetohydrodynamic relaxation. An important finding is that the relaxation takes the form of either global relaxation (e.g., the reversed field pinch relaxation) or local relaxation (e.g., the tokamak sawtooth relaxation), depending on whether the driven reconnection is total (antiparallel) or partial (partially antiparallel). [ABSTRACT FROM AUTHOR]