Typical proton trajectory from population “B” in the many particle simulation, with initial position x = (−0.54,0.78,0.31)L₀ and velocity v = (−0.004, −0.006,0.002)v_Ae. The dashed lines show the projection of the magnetic field from the plane of motion, φ ≈ 110°, onto the y − z plane. Inset shows the motion in the x − y plane close to the spine axis. The purple arrows show the direction and relative magnitude of the gradient drift velocity and the dash-dotted lines show contours of the electric potential, with the intersecting tick mark indicating lower potential to the right.