Nonlinear finite-Larmor-radius effects in reduced fluid models

The polarization magnetization effects associated with the dynamical reduction leading to the nonlinear gyrokinetic Vlasov–Maxwell equations are shown to introduce nonlinear finite-Larmor-radius FLR effects into a set of nonlinear reduced-fluid equations previously derived by the Lagrangian variational method A. J. Brizard, Phys. Plasmas 12, 092302 2005 . These intrinsically nonlinear FLR effects, which are associated with the transformation from guiding-center phase-space dynamics to gyrocenter phase-space dynamics, are different from the standard FLR corrections associated with the transformation from particle to guiding-center phase-space dynamics. We also present the linear dispersion relation results from a nonlinear simulation code using these reduced-fluid equations. The simulation results in both straight dipole geometries demonstrate that the equations describe the coupled dynamics of Alfvén sound waves and that the total simulation energy is conserved. © 2008 American Institute of Physics. DOI: 10.1063/1.2965827