Nonlinear finite-Larmor-radius effects in reduced fluid models

摘要

The polarization and magnetization effects associated with the dynamicalreduction leading to the nonlinear gyrokinetic Vlasov-Maxwell equations areshown to introduce nonlinear finite-Larmor-radius effects into a set ofnonlinear reduced-fluid equations previously derived by Lagrangian variationalmethod [A.J. Brizard, Phys. Plasmas 12, 092302 (2005)]. These intrinsicallynonlinear FLR effects, which are associated with the transformation fromguiding-center phase-space dynamics to gyrocenter phase-space dynamics, aredifferent from the standard FLR corrections associated with the transformationfrom particle to guiding-center phase-space dynamics. We also present thelinear dispersion relation and results from a nonlinear simulation code usingthese reduced-fluid equations. The simulation results (in both straight anddipole geometries) demonstrate that the equations describe the coupled dynamicsof Alfven and sound waves and that the total simulation energy is conserved.