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Gyrofluid turbulence models with kinetic effects

Journal Article · · Physics of Fluids B; (United States)
DOI:https://doi.org/10.1063/1.860934· OSTI ID:6742574
;  [1]
  1. Princeton University Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)

Nonlinear gyrofluid equations are derived by taking moments of the nonlinear, electrostatic gyrokinetic equation. The principal model presented includes evolution equations for the guiding center [ital n], [ital u][sub [parallel]], [ital T][sub [parallel]], and [ital T][sub [perpendicular]] along with an equation expressing the quasineutrality constraint. Additional evolution equations for higher moments are derived that may be used if greater accuracy is desired. The moment hierarchy is closed with a Landau damping model [G. W. Hammett and F. W. Perkins, Phys. Rev. Lett. [bold 64], 3019 (1990)], which is equivalent to a multipole approximation to the plasma dispersion function, extended to include finite Larmor radius effects (FLR). In particular, new dissipative, nonlinear terms are found that model the perpendicular phase mixing of the distribution function along contours of constant electrostatic potential. These FLR phase-mixing'' terms introduce a hyperviscositylike damping [proportional to][ital k][sub [perpendicular]][sup 2][vert bar][Phi][sub [bold k]k][times][bold k][prime][vert bar], which should provide a physics-based damping mechanism at high [ital k][sub [perpendicular]][rho] which is potentially as important as the usual polarization drift nonlinearity. The moments are taken in guiding center space to pick up the correct nonlinear FLR terms and the gyroaveraging of the shear. The equations are solved with a nonlinear, three-dimensional initial value code. Linear results are presented, showing excellent agreement with linear gyrokinetic theory.

DOE Contract Number:
AC02-76CH03073
OSTI ID:
6742574
Journal Information:
Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 5:3; ISSN 0899-8221; ISSN PFBPEI
Country of Publication:
United States
Language:
English