Time-resolved axial LIF contours showing multiple ion velocity populations throughout the near-field plume. The normalization is the same as in Fig. 11. The data are obtained from (a) $(x,z)=(−12,10)$⁠, (b) $(x,z)=(−12,10)$⁠, (c) $(y,z)=(−36,2)$⁠, (d) $(y,z)=(−20,2)$⁠, and (e) $(x,z)=(−20,2)$⁠.