Arrangement of Dots in a Sparse–Dense Dots Concentric-Ring Pattern in Dielectric Barrier Discharge

The sparse-dense-dot concentric-ring pattern is observed in dielectric barrier discharge in air/argon for the first time. It is an interleaving of two sets of circles; in one set, the dots arrange sparsely, while in the other, the dots array densely. The pattern shows periodicity not only along the radial direction but also along the azimuthal direction. The numbers of the dots in each set approximately form an arithmetical progression, respectively.