Particle velocity distributions corresponding to the spatial region (x = 0–2d_i, y = 0–2d_i). (a) Electron 2D velocity distribution in the v_∥ − v_⊥ space. Red crosses mark fast magnetosonic speed v_f and resonant speed ﹩{v}_{{\rm{res}}}﹩. (a1) Electron parallel velocity distribution, with dashed lines indicating v_f and ﹩{v}_{{\rm{res}}}﹩. The light red lines indicate the difference between the two histograms. (a2) Electron perpendicular velocity distribution. The blue histogram shows the initial distribution at t = 0, and the red histogram corresponds to t = 1.55τ_A − 1.6τ_A. (b) Proton 2D velocity distribution in the v_∥ − v_⊥ space. Red crosses mark v_f and ﹩{v}_{{\rm{res}}}﹩. (b1) Proton parallel velocity distribution, with dashed lines indicating v_f and ﹩{v}_{{\rm{res}}}﹩. (b2) Proton perpendicular velocity distribution. The blue histogram shows the initial distribution at t = 0, and the red histogram corresponds to t = 1.55τ_A − 1.6τ_A. The green dashed lines represent a kappa distribution fit with κ = 4.2.