ON THE DIFFUSION OF IMPURITIES IN TOKAMAK PLASMA

We investigate the influence of the magnetic Kubo number, the drift Kubo number and stochastic anisotropy on the diffusion of ions in turbulent, stochastic magnetic fields, applying the decorrelation trajectory method (DCT) and using test-particle simulations. It turns out that the stochastic drifts provide a decorrelation mechanism for the particles from the magnetic lines, and trapping effects are more pronounced, the stronger the magnetic perturbation and the larger the anisotropy in it is. The diffusion coefficients yielded by test particle simulations are in qualitative agreement with those obtained from the DCT method.