Acceleration history of four representative high-energy ion trajectories tracked from their injection at ω_pit = 175 up to ω_pit ≳ 2000 where they have all reached the jet confinement limit. Top: full ion trajectory superimposed onto the final plasma density map (gray scale). The color indicates the particle Lorentz factor γ_i, while the marker size codes for the acceleration rate , where ω₀ = eB₀/m_ic, a large marker means a high positive rate while a small marker is for negative rates. Bottom: time evolution of the ion Lorentz factor (blue solid line) and acceleration rate (red dashed line).