Influence of Magnetic Turbulence on Charged Particle Drift

By means of direct numerical simulation we investigate the large scale drift of protons in a non-uniform magnetic field. This is achieved by using a large scale magnetic field that varies in the direction perpendicular to the mean field direction. This leads to the well-known gradient drift of the particles which is perpendicular to both the gradient in the field as well as the mean field direction. We calculate directly the drift velocity of the ensemble from the particle trajectories. To make the connection to a more physical configuration, a random component is added to the large scale magnetic field to introduce turbulent particle scattering. We find that when the amplitude of the fluctuations is sufficiently small, the ensemble drifts at the classical weak scattering drift velocity. However, when the amplitude of the fluctuations is sufficiently large, the ensemble drift velocity is effectively nullified. We aim to use the results from this study in an advanced ab initio cosmic ray modulation model. Supported by NASA grant NNG04GF81G.