Studying the dynamic parameters of the plasma pellet produced byhelium jet in the presence of different ambient gases

In this paper, dynamical parameters of a plasma bullet (guided ionization wave) were studied in different gases such as oxygen, nitrogen and dry air. The dynamics of a plasma bullet, which is generated by a 30 kHz atmospheric pressure helium plasma jet, was measured using a high-speed ICCD camera from the starting moment of propagation at the end of the jet’s capillary to the vanishing point in the surrounding gas. The plasma bullet has different propagation velocity, diameter and propagation length in different surrounding gases. The velocity of the plasma bullet is higher in oxygen and dry air compared to nitrogen and reaches up to 18 km/s. The maximum propagation length is 12 mm in nitrogen and dry air. The spectroscopic emission of helium plasma jet was also measured to investigate the chemical species in different surrounding gases. The result of this study shows the influence of the surrounding gas on the propagation of plasma bullets and especially the role of oxygen in the propagation mechanism.