Plasma bullets behavior in a tube covered by a conductor

Abstract

In this work, for better applications of atmospheric pressure plasma jets, the physics of plasma streamers in a glass tube with a part of it covered by a conductor is investigated. To better understand the propagation mechanism of plasma bullets in capillary tubes passing through a curved or narrow passage for some biomedical or material applications, the propagation of plasma streamers in a tube covered by a floating conductor is investigated. For a plasma streamer propagating in a tube covered by a conductor, the plasma streamer is suppressed and becomes shorter, and a secondary streamer is generated in the tube at the downstream end of the conductor. The larger the area covered by the conductor, or the thinner the tube, the stronger the plasma streamer is inhibited. The electric potential of the conductor is measured to be as high as 6 kV. On the other hand, a higher voltage applied on the HV electrode, or a higher gas flow rate will make the secondary plasma streamer longer. It is found that the capacitor formed by the conductor outside the tube and the wall of the tube plays an important role in inhibiting the original plasma streamer and generating the secondary streamer. Moreover, the active species generated by the original plasma play important role in generating a secondary plasma streamer.

Effect of external electric field on helix plasma plume

“…In general, when a plasma is generated in a dielectric tube, it is believed that the dielectric tube will affect the plasma because of the charge accumulation on the inner surface of the quartz tube [37][38][39][40][41]. To understand the effect of the quartz tube on the plasma characteristics, studies with tube radius varied from micrometer to centimeter have been reported [42][43][44][45]. Investigations on the dynamic behavior of the plasmas generated in the tubes showed that most of them propagate in straight line.…”

Dynamics of ionisation wave propagation in an applied external electric field

“…In this case, the ring electrode can be treated as a floating electrode. Previous studies suggest that the floating electrode in front can facilitate the propagation of the IW due to its relative low electric potential [30, 31]. The peak values of the discharge currents in Figs.…”

“…This indicates that the electrical potential of the floating ring electrode is higher than 2.86 kV. By using the equal effect method [31], the electrical potential of the floating ring electrode was calculated to be about 3.1 kV.…”