ION PLATEAU TRANSPORT NEAR THE TOKAMAK MAGNETIC AXIS

Conventional neoclassical transport theory does not pertain near the m agnetic axis, where orbital variation of the minor radius and the polo idal field markedly change the nature of guiding-center trajectories. Instead of the conventional tokamak banana-shaped trajectories, near-a xis. orbits, called potato orbits, are radially wider and lead to dist inctive kinetic considerations. Here it is shown that there is a plate au regime for the near-axis case; the corresponding potato-plateau ion thermal conductivity is computed. (C) 1998 American Institute of Phys ics.