Back-propagated ion trajectories for Run 2. The color of the trajectory shows the particle energy in the vicinity of the nucleus (approximately virtual particle collection energy), with the blue-red turnover at the knee energy. The green dots along the trajectories show points on the trajectories where the particle kinetic energy on the trajectory is lower than 4 eV, approximating possible points of pickup ion production. On the Y = 0 plane, the magnetic field magnitude in grayscale and the convective electric field arrows (purple) are shown for context. The M_ms = 2 contour is shown in red.