Figure 4

Spatially resolved light emission intensities along the middle discrete discharge with a gap width of 5 mm (a) and the symmetrical axis of the planar discharge with a gap width of 15 mm (b).
Spatially resolved light emission intensities along the middle discrete discharge with a gap width of 5 mm (a) and the symmetrical axis of the planar discharge with a gap width of 15 mm (b).