Wave spectrum I(k) of right-handed and left-handed polarisation waves (top panels: a, d, and g), spatial profile of magnetic field fluctuations δB_y,z/B₀ (middle panels: b, e, and h) and distribution function of beam electrons and positrons f(V_x) and different times of the simulation (bottom panels: c, f, and i). Left column corresponds to early time (tΩ_ci = 7.6), middle column to the linear phase (tΩ_ci = 76) and right column to the saturated phase of the instability (tΩ_ci = 186).