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 pi R(0)q) along helical magnetic-field lines that are diffusing radially with the resistivity-induced magnetic-field diffusivity D-eta=eta(nc)(parallel to)/mu(0)similar or equal to nu(e)(c/omega(p))(2). This produces a paleoclassical radial electron heat diffusivity chi(pc)(e) that is a multiple M similar or equal to L/(pi R(0)q)similar to 10 > 1 of the magnetic-field diffusivity: chi(pc)(e)similar or equal to(3/2)MD eta . 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 drift kinetics via a Fokker-Planck procedure, and determination of both axisymmetric and the usually dominant helically resonant paleoclassical radial electron heat transport. (C) 2005 American Institute of Physics.