MAGNETOHYDRODYNAMIC EQUATIONS FOR PLASMAS WITH FINITE-LARMOR-RADIUS EFFECTS

It is shown that the truncation of the infinite hierarchy of fluid equ ations obtained as moments of the Vlasov kinetic equation leads to a s ystem of nonlinear equations that describe finite-larmor-radius effect s with good accuracy. Inertial terms in the momentum balance, viscosit y and heat-flux evolution equations are crucial for a uniform descript ion of the plasma response with an arbitrary Larmor radius. In the low -frequency ordering, the obtained equations are simplified by an expan sion in the parameter 1/B, where B is the equilibrium magnetic field. The results of the second-order O(1/B-2) and the fourth-order O(1/B-4) closures are compared. It is shown that the accuracy of the descripti on improves for higher-order closures.