Properties of a cutout along the x-axis of the lower part of the EB (indicated as a white box in Figs. 1 and 3). Top left to right: frequency-integrated ionizing radiation field J_ion (see Eq. (9)), where j_ion, abs is absorbed (see Eq. (14)), and total number of recombinations in the triplet system N_rec as defined Eq. (15). Bottom: composite panel of J_ion, j_ion, abs, and N_rec. The black markers indicate the position of the He I D₃ profile shown in Figs. 6 and 8 at locations L_em (see Fig. 5) and h_em (see Fig. 8). The black contours show the regions in which erg s⁻¹ cm⁻³ ster⁻¹, see also Eq. (13).