Flower-Shaped Strata

Photograph images of 3-D standing ionization waves (i.e., strata) in the shape of crabs and flowers are obtained in a dc glow discharge in air at moderate pressure (10-30 torr). The main idea of such 3-D strata is based on creating conditions for free propagation of ionization waves in all directions. These conditions may be reached with a glass cylinder of large diameter (155 mm) and electrodes of small diameters (25 mm).