Study of the interaction between two counter-propagating plasma bullets

摘要

Cold plasma jets produced by pulsed discharges have recently attracted a lot of attention because of their unusual physical properties enabling the development of new applications, particularly for plasma medicine. ICCD pictures of these jets revealed that they were not continuous plasmas but composed of plasma bullets propagating at very high velocity. In this paper, pictures of the interaction of two counter-propagating plasma bullets have been taken to give insights into the physics of these bullets. Our results show that a secondary bullet appears whenever there are two switched-on discharges with two counter-propagating helium flows. For discharge conditions corresponding to one gas flow and two switched-on discharges, a pink glow can be readily observed between the two plasma plumes. Time-resolved imaging studies point out that this pink glow appears only a few nanoseconds after the collapses of the plasma bullets, and that the size and the location of this pink glow exactly correspond to the area free of previous plasma bullet propagation.