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

This paper discusses the stochastic (E x B) motion of ions in the homogeneo us magnetic held and in the spatially periodical electrostatic potential. T his approach is used for the simulation of ion diffusion in potential struc tures formed at the boundary plasma in tokamaks. We show that the ion motio n in such structures scales with a single dimensionless parameter R, which is a combination of amplitude and dimension of potential structures, magnet ic held intensity and ion charge/mass ratio. The presented results show tha t for sufficiently large values of R, the intrinsic stochasticity regime of ion motion appears, which results in the spatial diffusion of ions. The di ffusion coefficient is sufficiently high for heavy impurities. Possible fur ther applications are mentioned.