Motion of solar cosmic rays in the coronal magnetic field

Trajectories of solar cosmic rays have been calculated in a static ninth-order coronal magnetic field. It is found that as a result of field curvature and gradients, protons drift across the field lines at a rate of up to 200 γβ2 deg hr.-1 These drift rates are of the same order as, but somewhat smaller than, empirically derived rates. Localized enhancements of magnetic field have been inserted into the ninth-order field in order to model (in a highly idealized manner) the effects of the small-scale magnetic features which give rise to X-ray bright points. The motions of the particles in the presence of these scattering centres can be parementreized approximately by a cross-field diffusion coefficient. It is proposed that coronal propagation of solar cosmic rays has two components. One is independent of particle velocity, and is associated with dynamic field phenomena (such as an expanding magnetic bottle). The second component is velocity dependent, but is independent of mass and is associated with scattering off (relatively static) magnetic inhomogenities with scale sizes of at least 500 km. (Auth.)