Rare gas flow structuration in plasma jet experiments

Abstract

Modifications of rare gas flow by plasma generated with a plasma gun (PG) are evidenced through simultaneous time-resolved ICCD imaging and schlieren visualization. The geometrical features of the capillary inside which plasma propagates before in-air expansion, the pulse repetition rate and the presence of a metallic target are playing a key role on the rare gas flow at the outlet of the capillary when the plasma is switched on. In addition to the previously reported upstream offset of the laminar to turbulent transition, we document the reverse action leading to the generation of long plumes at moderate gas flow rates together with the channeling of helium flow under various discharge conditions. For higher gas flow rates, in the l min −1 range, time-resolved diagnostics performed during the first tens of ms after the PG is turned on, evidence that the plasma plume does not start expanding in a laminar neutral gas flow. Instead, plasma ignition leads to a gradual laminar-like flow build-up inside which the plasma plume is generated. The impact of such phenomena for gas delivery on targets mimicking biological samples is emphasized, as well as their consequences on the production and diagnostics of reactive species.

Safety aspects of atmospheric pressure helium plasma jet operation on skin: In vivo study on mouse skin

“…Namely, the flow rate can bring reactive species further away from the end tip of the tube (tube orifice) where plasma is generated to the surface. Moreover, increased flow rates can also increase or shorten the plasma jet length as well as bring plasma from almost laminar to more turbulent flow state [18–22]. Similarly as the jet flow is interacting with the surface, gaseous reactive species are spread over surface [22].…”

“…Moreover, increased flow rates can also increase or shorten the plasma jet length as well as bring plasma from almost laminar to more turbulent flow state [18–22]. Similarly as the jet flow is interacting with the surface, gaseous reactive species are spread over surface [22]. Additional influence can also come from so-called coupling of jet with the surface, where streamers are formed and higher currents are driven onto the skin.…”

Investigation of gas flow dependence of plasma jet produced by pulsed power

“…5 [16]. Consideration of flow contraction ratio-a transition to turbulent flow at Re = 200 or more-is necessary as it is considered that plasma is disturbed [16], [17] and light emission is shortened at those levels.…”

Single channel atmospheric pressure transporting plasma and plasma stream demultiplexing: physical characterization and application toE. colibacteria inactivation

“…The propagation of plasma bullets in a cold plasma jet has been widely studied, and the influence of the discharge parameters on the plume characteristics has been reported [14][15][16][17][18][19]. In order to meet adequately various customers' needs, it is necessary to develop different plasma sources, especially, those which can generate long transporting plasma strings meant for treatment of remote downstream targets.…”