The spatial and temporal development of ionization waves along one dielectric tube

Atmospheric pressure plasma bullets or ionization waves have been generated in one long (Φ 2 mm × 100 mm) dielectric tube filled with He gas when a sinusoidal AC high-voltage with its frequencies of 9.0 kHz is applied between the tungsten pin electrodes. ICCD measurements show that the propagation of ionization waves in I, U and O tubes is anode-driven electrically, and the spatial and temporal development of ionization waves is strongly dependent on the He flow rate and applied voltage. Three stages are clearly observed during the propagation of ionization waves along the tube, and their propagation process is discussed based on the experimental results. The generation and propagation of ionization waves in the tube are affected by many physical processes, such as the drift motion of He⁺ ions or excited species, the distribution of plasma potential along the dielectric tube, the surface recombination of charged species, He⁺-induced electron emission from the pin cathode, and so on.