The standard explanation for Anomalous Cosmic Rays requires strong energization at the heliospheric termination shock. However, the tightly wrapped magnetic spiral in the outer heliosphere produces a quasi-perpendicular shock where it is difficult to accelerate low energy particles. We show that motion of footpoints between regions of fast and slow solar wind at the Sun, create non-spiral configurations and large radial components of the magnetic field. These regions preferentially inject low energy particles into diffusive shock acceleration. Further, footpoints that move from slow to fast source regions, generate field lines with local polarity inversions that connect to the termination shock at multiple locations. As these regions convect out, they trap particles between what are effectively two converging shocks, producing additional first-order Fermi acceleration. Heliospheric "FALTS" - Favored Acceleration Locations at the Termination Shock - should play an important role in particle acceleration in the outer heliosphere.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)