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 R0q along helical magnetic-field lines that are diffusing radially with the resistivity-induced magnetic-field diffusivity D / 0 e c / p 2. This produces a paleoclassical radial electron heat diffusivity e pc that is a multiple M L / R0q 10 1 of the magnetic-field diffusivity: e pc 3/2 MD . 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. © 2005 American Institute of Physics. DOI: 10.1063/1.2047227