Position of the separator during Phase 1. (a) Height (z_s) of the separator as a function of the half-separation (d) for different values of the minority flux (F_p). The coloured points mark the locations of the maximum z_s (green) and the critical points where z_s = 0 for d = d_c1 (blue) and d = d_c2 (red). (b) Horizontal position (x_s) of the separator as a function of d. (c) Positions (x_s, z_s) of the separator in the y = 0 plane as d varies for different values of F_p.