UW-CPTC 04-3 (Revised3) Paleoclassical transport in low collisionality toroidal plasmas

Radial electron heat transport in a low collisionality, current-carrying resistive plasma confined in an axisymmetric toroidal magnetic field is hypothesized to be caused by the paleoclassical collisional processes of parallel electron heat conduction and radial magnetic field diffusion. The electron distribution is Maxwellianized and the electron temperature equilibrated over a long length L (>> the poloidal periodicity half-length πR0q) along helical magnetic field lines that are diffusing radially with the resistivity-induced magnetic field diffusivity Dη ≡ η ‖ /μ0 ' νe(c/ωp). This produces a paleoclassical radial electron heat diffusivity χ e that is a multiple M ' L/(πR0q) ∼ 10 >> 1 of the magnetic field diffusivity: χ e ' (3/2)M Dη. New paleoclassical model developments in this paper include: full axisymmetric toroidal magnetic field geometry, evolution of toroidal, poloidal, and helical magnetic fluxes, effects of temporally varying magnetic fluxes, introduction of electron guiding center radial diffusion effects induced by poloidal magnetic flux diffusion into electron driftkinetics via a Fokker-Planck procedure, and determination of both axisymmetric and the usually dominant helically resonant paleoclassical radial electron heat transport.