Cross-sectional view of an ejecta curtain and a schematic illustration of ejected particles, constructed according to the theoretical model in cylindrical coordinates (r, z). Particles move along the streaming lines, and are then ejected from the surface at a velocity of v_e (x) at an angle of θ. Particles ejected from (x, 0) and (x +Δx, 0) at the time of impact reach points A and B at time t, composing the front surface of the ejecta curtain.