A GENERAL-SOLUTION OF THE RIPPLE-AVERAGED KINETIC-EQUATION (GSRAKE)

A general solution of the ripple-averaged kinetic equation, GSRAKE, is presented and used to investigate neoclassical transport in the model magnetic field of a simple stellarator. No assumptions are made as to the relative sizes of the collision frequency, upsilon, and poloidal precessional frequency, Omega(theta), so that the solution is valid throughout the entire long-mean-free-path regime. Separate but fully self-consistent treatments of both localized and non-localized particles are provided; the interaction between these two classes of particles is accounted for through a set of appropriate physical boundary conditions. All drift terms present within the framework of the ripple-averaged theory are included; in particular, for localized particles Omega(theta) = Omega(E) + Omega(del B) is comprised of both the E x B and del B precessional frequencies. The solution is thus equally valid in the Omega(E) much greater than Omega(del B) and the Omega(E) = 0 limits of standard neoclassical theory. A detailed comparion of results with those of the FLOCS code is undertaken; estimates of neoclassical transport coefficients obtained from several codes are also presented. Good agreement of results is found in all of these comparisons, GSRAKE requiring but a tiny fraction of the computational time necessary for the other codes.