Electron velocity distribution functions for Run 1 (a)–c)) and Run 2 (d)–f)) at times respectively. The solid line shows the velocity distribution aligned with the beam (v_x) and the dashed line shows the transverse velocity (v_y). Panels g) and h) are representative of the behaviour in 2D phase-space for Run 1 and 2 respectively at . Note the plateau formation in v_x with the saturation of the bump-in-tail instability, and the transverse heating of the beam electrons due to the Weibel instability.