Dynamics of ionization wave splitting and merging of atmospheric-pressure plasmas in branched dielectric tubes and channels
نویسندگان
چکیده
Atmospheric-pressure fast ionization waves (FIWs) generated by nanosecond, high voltage pulses are able to propagate long distances through small diameter dielectric tubes or channels, and so deliver UV fluxes, electric fields, charged and excited species to remote locations. In this paper, the dynamics of FIW splitting and merging in a branched dielectric channel are numerically investigated using a two-dimensional plasma hydrodynamics model with radiation transport, and the results are compared with experiments. The channel consists of a straight inlet section branching 90◦ into a circular loop which terminates to form a second straight outlet section aligned with the inlet section. The plasma is sustained in neon gas with a trace amount of xenon at atmospheric pressure. The FIW generated at the inlet approaches the first branch point with speeds of ≈108 cm s−1, and produces a streamer at the inlet–loop junction. The induced streamer then splits into two FIW fronts, each propagating in opposite directions through half of the loop channel. The FIWs slow as they traverse the circular sections due to a shorting of the electric field by the other FIW. Approaching the loop–outlet junction, the two FIW fronts nearly come to a halt, induce another streamer which goes through further splitting and finally develops into a new FIW front. The new FIW increases in speed and plasma density propagating in the straight outlet channel. The electrical structure of the FIWs and the induced streamers during the splitting and merging processes are discussed with an emphasis on their mutual influence and their interaction with the channel wall. The FIW propagation pattern is in good agreement with experimental observations. Based on numerical and experimental investigations, a model for the splitting and merging FIWs in the branched loop channel is proposed. (Some figures may appear in colour only in the online journal)
منابع مشابه
Second Harmonic Reduction of Traveling Wave Tube Amplifier Using Ferrite Material
Traveling Wave Tubes (TWTs) consist of different elements. The most important element of TWT is the RF circuit. RF circuits in helix TWTs need a dielectric support to hold the helix; this support also has an effect in electromagnetic properties of RF circuits. A novel dielectric support is proposed to reduce the second harmonic of helix TWTs. The dielectric support in this structure consists of...
متن کاملAtmospheric-pressure plasma transfer across dielectric channels and tubes
Atmospheric-pressure plasma transfer refers to producing an ionization wave (IW) in a tube or channel by impingement of a separately produced IW onto its outer surface. In this paper, we report on numerical and experimental investigations of this plasma transfer phenomenon. The two tubes, source and transfer, are perpendicular to each other in ambient air with a 4 mm separation with both tubes ...
متن کاملInteraction of multiple atmospheric-pressure micro-plasma jets in small arrays: He/O2 into humid air
Arrays of atmospheric-pressure plasma jets are being considered as a means to increase the area being treated in surface modification and in plasma medicine in particular. A unique challenge of scaling plasma jet arrays is that individual plasma jets in an array tend to interact with each other, which can lead to quenching of some individual jets. To investigate these potential interactions, a ...
متن کاملAccurate characteristics of Helium in nano-channels
This article describes an accurate subPico flowmeter bifurcatedin to liquid and gas flowrates less than 1mol/s for both MEMS/NEMS and cryogenic technology applications. The MEMS/NEMS are described as either two Gauges (instrument), or quartz fluctuating forks, even if the liquid or gas flows through an element, as well as cryogenic technology consisting of arrays of e...
متن کاملHelium atmospheric pressure plasma jets touching dielectric and metal surfaces
Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinit...
متن کامل