Effects of Perpendicular Diffusion in the Radial Direction on the Acceleration of Particles at the Solar Wind Termination Shock

The role of radial perpendicular diffusion are illustrated in a numerical modulation model containing a heliosheath and diffusive shock acceleration as applied to the solar wind termination shock. Of particular interest is the relation of radial perpendicular diffusion to the effectiveness of the termination shock acceleration of galactic and anomalous protons and helium. We found that the enhancement of radial perpendicular diffusion in the polar direction has a prominent effect on acceleration of particles at the solar wind termination shock. It consequently may explain recent measurements of the Voyager 1 spacecraft at and beyond the shock, where the observed acceleration of the anomalous component of cosmic rays is apparently not as large as expected.