Snapshots of the jet with an injected perturbation. The jet is propagating from the bottom to the top along the Z axis. The electron number density contour (in log-scale) is drawn on the left side, and the maximum value of the electron Lorentz factor (also in log-scale) on the right side. Both radial coordinates R and Z are given in R_jet units. The generated moving shock wave is located at ∼20 R_jet (A), ∼70 R_jet (B), ∼120 R_jet (C), and ∼170 R_jet (D) from the jet base and is marked with a white star.