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Unified plasma fluid/kinetic equations for tokamak microinstability and turbulence studies

Technical Report ·
OSTI ID:5905656

Unified fluid/kinetic equations for the plasma perturbed density ({tilde n}), parallel flow velocity ({tilde u}{sub {parallel}}) and temperature ({tilde T}) are developed by calculating the fluid moment closure relations kinetically. At first, a set of (unclosed) perturbed fluid equations for {tilde n}, {tilde u}{sub {parallel}} and {tilde T} is developed using a drift ordering analysis and a new gyroviscous force ({del} {center dot} {Pi}{sub g}) derived from the stress tensor ({Pi}) evolution equation. Thereafter, to develop linear closure relations for b {center dot} {del} {center dot} {tilde {Pi}}{sub {parallel}} and {del} {center dot} {tilde q}, a drift-kinetic version of a Chapman-Enskog-type equation suitable for toroidal magnetic geometry is derived. In a sheared slab geometry this equation is solved using a moment approach and a physically realistic collision operator (Lorentz scattering operator plus the momentum restoring terms). The resultant closure relations for {tilde {pi}}{sub {parallel}} and {tilde q}{sub {parallel}} unify both the fluid and kinetic properties. In the fluid collisional limit the equations reduce to the well-known Braginskii equations. In the adiabatic limit they reproduce the usual kinetic results, including Landau damping. It is shown that the Chapman-Enskog-type approach is more compatible with a fluid-like description of plasmas than the usual gyrokinetic approach. Remarkable simplification of these complicated closure relations is achieved. The results are compared with other recently developed Landau damping models and shown to be more accurate and complete.

Research Organization:
Wisconsin Univ., Madison, WI (USA)
Sponsoring Organization:
DOE; USDOE, Washington, DC (USA)
DOE Contract Number:
FG02-86ER53218
OSTI ID:
5905656
Report Number(s):
UW-CPTC-91-2; ON: DE91011010
Country of Publication:
United States
Language:
English