ACR's and magnetic field at the heliospheric termination shock

Voyager 1 observations in the outer heliosphere and heliosheath impose important constraints on anomalous cosmic ray (ACR) acceleration at the heliospheric termination shock. The three-dimensional, vector anisotropies (radial, azimuthal and latitudinal) depend in an important way the large-scale structure of termination shock. In particular, the observations can be understood if the shape of the termination shock is not spherical, both globally and on a small scale. We have shown previously that all three components of the anisotropy may be understood if the global shape of the termination shock is as expected from simulation and analogy. Similarly, radial motion of the termination shock can change the intensity and energy spectra both upstream of the shock and in the heliosheat. Recent observations of the magnetic field from the Voyager 1 spacecraft, where, in the heliosheath, the magnetic field has remained directed outward from the Sun for several months. We show that this is a result rapid inward motion of the termination shock. The implications for the energy spectrum are also discussed.