Electric fields in the x–z plane (top row) and x–y plane (bottom row) from both the analytical model and simulation run C. Panels (a) and (f) show the convective electric field of the analytical model; (b) and (g) the ambipolar field; (c) and (h) the polarisation field; (d) and (i) the sum of the three electric field contribution in the analytical model; and panels (e) and (j) show the electric field obtained in run C of the particle-in-cell simulation.