Particle energy spectrum in the plasma rest frame for escaping particle populations upstream of the shock for shock obliquities 70°, 80°, and 85° (top) and 86°, 87°, and 88° (bottom). The box size used in the simulations corresponds to a 1 keV particle’s diffusion length upstream and downstream of the shock along the magnetic field line. The mean free path profile, λ_trans, was used.