Effect of Gas Impurities on the Operation of Dielectric Barrier Discharges Fed with He, Ar, and Ar‐C₃F₆

Abstract

The influence of N 2 , O 2 , air, and water vapor feed gas impurities on the operation of an atmospheric pressure parallel plate DBD fed with helium and argon was investigated. The addition of increasing amounts of these impurities, under fixed excitation frequency and applied voltage, is responsible above certain thresholds of two distinct phenomena, namely the transition from a homogeneous to a filamentary appearance of the discharge and the contraction of the discharge volume. Among the different contaminants N 2 shows the highest threshold limit values, O 2 and H 2 O the lowest ones, while air generally exhibits an intermediate behavior. The effect of feed gas impurities was also studied on the PE-CVD of fluoropolymers from Ar-C 3 F 6 fed filamentary DBDs. Contaminants addition results in a decrease of the input power and of the deposition rate as well as in a change of the film morphology, however it does not influence significantly the chemical composition of the fluoropolymer film, the monomer depletion and the distribution of by-products in the exhaust gas. 0.00 0.05 0.10 0.15 0.20 0.0 0.5 1.0 1.5 2.0 [Additive] (%) N 2 O 2 Air H 2 O

Atmospheric Pressure Low Temperature Direct Plasma Technology: Status and Challenges for Thin Film Deposition

“…The contaminant concentration in the reactor is likely always the same and the important parameter is the ratio of this contamination and the thin film precursor. Another important point to have in mind is oxygen etching: the investigation of influence of air and water vapor contaminations on the AP deposition of fluorocarbon coatings in Ar–C 3 F 6 FDBDs145 have shown, surprisingly, that the contaminants addition (at contaminant‐to‐C 3 F 6 feed ratios as high as 0.5) did not appreciably affect the chemical composition (i.e., constant XPS F/C ratio and O‐ and N‐uptake lower than 1%) and the hydrophobic character of the deposited coatings. On the other hand, it resulted in a decrease of the discharge power, of the deposition rate and the appearance of a certain roughness; these changes were more evident for the addition of O 2 , air, and H 2 O than for N 2 .…”

Diffuse Coplanar Surface Barrier Discharge in Artificial Air: Statistical Behaviour of Microdischarges

“…For the generation of homogeneous volume DBDs at atmospheric pressure the use of noble gasses or pure nitrogen is necessary -as in the case of e.g. APGD or APTD [36][37][38][39]. Contrary to the previously mentioned DBD configurations the DCSBD is capable of generating a macroscopically uniform plasma layer with high power density and energetic efficiency when operated in air [40,41].…”

Direct Exposure of Dry Enzymes to Atmospheric Pressure Non-Equilibrium Plasmas: The Case of Tyrosinase

“…Pure He. Helium is used in large amount, as main gas, in many AP plasma processes [27,35,36,39,[51][52][53][54][55][56][57]. DBDs fed by a pure noble gas (e.g., helium or argon) are often exploited for the plasma treatment of organic materials, i.e., to induce moderate changes in the surface roughness as well as in the chemical composition of the outermost layers of these materials [27,[55][56][57].…”