Analytical modeling of equilibrium of strongly anisotropic plasma in tokamaks and stellarators

Theoretical analysis of equilibrium of anisotropic plasma in tokamaks and stellarators is presented. The anisotropy is assumed strong, which includes the cases with essentially nonuniform distributions of plasma pressure on magnetic surfaces. Such distributions can arise at neutral beam injection or at ion cyclotron resonance heating. Then the known generalizations of the standard theory of plasma equilibrium that treat p (aEuro-) and p (aSyen) (parallel and perpendicular plasma pressures) as almost constant on magnetic surfaces are not applicable anymore. Explicit analytical prescriptions of the profiles of p (aEuro-) and p (aSyen) are proposed that allow modeling of the anisotropic plasma equilibrium even with large ratios of p (aEuro-)/p (aSyen) or p (aSyen)/p (aEuro-). A method for deriving the equation for the Shafranov shift is proposed that does not require introduction of the flux coordinates and calculation of the metric tensor. It is shown that for p (aSyen) with nonuniformity described by a single poloidal harmonic, the equation for the Shafranov shift coincides with a known one derived earlier for almost constant p (aSyen) on a magnetic surface. This does not happen in the other more complex case.