Helical Plasma Propagation of Microsecond Plasma Gun Discharges

Atmospheric pressure helium plasma inside a dielectric capillary and in the plume may exhibit stable and fascinating helix patterns. Such plasma propagation mode is achieved over an extended range of pulse repetition and gas flow rates. A key role of electric field is inferred from voltage, and electromagnetic configuration perturbation impacts on the plasma pattern. Helical plasma propagation is suggested to represent a specific case of previously reported wall-hugging plasma propagation.