Kinetic energy evolution for 50,000 particles evolved in the MHD-PIC simulation for the σ ∼ 1 (top) and for the σ ∼ 10 (bottom) jet. Particles are initially injected with energy ﹩\left\langle {E}_{p}\right\rangle \sim 1-200{m}_{p}{c}^{2}﹩. The colors indicate which velocity component of the particles is being accelerated (red or blue for the parallel or perpendicular component to the local magnetic field, respectively). The inset panels depict the evolution of the particle’s gyroradius, and the red horizontal lines correspond to the jet diameter (4L; top) and the cell size of the simulated jet (bottom).