Stochastic (E x B) diffusion of ions in a spatially periodical potential field

In this contribution, the stochastic (E x B) motion of ions in a homogeneou s magnetic field and in a spatially periodical electrostatic potential is d iscussed. This approach is used for the simulation of ion diffusion in pote ntial structures formed at the boundary plasma in tokamaks. Nonintegrabilit y of the system causes the spatial diffusion of ions. Depending on the choi ce of parameters, this diffusion has either the usual random-walk character , or appears, for sufficiently strong nonlinearity, in the form of Levy wal ks. The diffusion coefficient is sufficiently high for heavy impurities. Po ssible further applications are mentioned.