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The paper investigates the role of relative motion between the fluid components of a plasma model, which is simulated by concatenation of two anisotropic magnetohydrodynamic (MHD) fluids, on the propagation of low-frequency waves and instabilities. The gyrotropic pressure of both the MHD components is given by generalized polytropic laws that allow the system to reduce to a variety of states. The linearized analysis is carried out and dispersion relation is derived using the normal mode technique. The dispersion relation, which gives numerous earlier results as special cases, is discussed both analytically as well as numerically for parameters appropriate for the space plasma. It is found that the relative motion between the two components, besides modifying the condition for fire-hose instability, causes the concatenated system to exhibit different kinds of relative ordering of the magnitudes of phase speeds of the various MHD modes in the directions parallel and antiparallel to the magnetic field. The relative motion between the components also influences the phase relationship between density and magnetic field fluctuations for the various compressive modes in the background ambient plasma. [ABSTRACT FROM AUTHOR]

Adopting the theoretical framework for the generalized fishbonelike dispersion relation, an extended hybrid magnetohydrodynamics gyrokinetic simulation model has been derived analytically by taking into account both thermal ion compressibility and diamagnetic effects in addition to energetic particle kinetic behaviors. The extended model has been used for implementing an extended version of hybrid magnetohydrodynamics gyrokinetic code (XHMGC) to study thermal ion kinetic effects on Alfvénic modes driven by energetic particles, such as kinetic beta induced Alfvén eigenmodes in tokamak fusion plasmas. The XHMGC nonlinear model can be used to address a number of problems, where kinetic treatments of both thermal and supra-thermal plasma components are necessary, as theoretically predicted, or where it is desirable to investigate the phenomena connected with the presence of two supra-thermal particle species with different radial profiles and velocity space distributions. [ABSTRACT FROM AUTHOR]

The linear and nonlinear evolution of a single-helicity tearing mode in a cylindrical, force-free pinch are investigated using a fluid model with first-order finite-Larmor-radius corrections. Linear results computed with the nimrod [nonideal magnetohydrodynamics (MHD) with rotation, open discussion] code [Sovinec et al., J. Comput. Phys. 195, 355 (2004)] produce a regime at small ρs where the growth rate is reduced relative to resistive MHD, though the Hall term is not significant. The leading order contributions from ion gyroviscosity may be expressed as a drift associated with ∇B0 and poloidal curvature for experimentally relevant β=0.1, S~105-106 force-free equilibria. The heuristic analytical dispersion relation, γ4(γ-iω*gv)=γMHD5 where ω*gv is the gyroviscous drift frequency, confirms numerical results. The behavior of our cylindrical computations at large ρs corroborates previous analytic slab studies where an enhanced growth rate and radially localized Hall dynamo are predicted. Similar to previous drift-tearing results, nonlinear computations with cold ions demonstrate that the Hall dynamo is small when the island width is large in comparison with the scale for electron-ion coupling. The saturation is then determined by the resistive MHD physics. However, with warm ions the gyroviscous stress supplements the nonlinear Lorentz force, and the saturated island width is reduced. [ABSTRACT FROM AUTHOR]