Solution to the mixed Ohmic and ambipolar diffusion problem of Eqs. (11) and (12), in which the inset shows the whole range −L₀ ≤ x ≤ L₀) and the main frame shows just the central domain −0.018L₀ ≤ x ≤ 0.018L₀)]. Green: Exact solution (16). Blue: Purely ambipolar solution (17). Dashed red: Linear, purely Ohmic solution with slope at the origin equal to that of the full solution (19). Pink: Linear purely Ohmic solution linking the points ( − L₀, −B₀) and (L₀, B₀). The dotted vertical lines mark the locations x = ±l_d. The blue and green curves and the red segment appear superimposed in the inset.