Filters

20202

More filters

20212
Reset filters

Settings

End date: 2024 × Start date: 2020 × DDC: 530 × Has files: Yes × Subject: argon × WGL Institute: INP ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Does the energy transfer from Ar(1s) atoms to N2 lead to dissociation?
    (Hoboken, NJ : Wiley Interscience, 2020) Klages, Claus‐Peter; Martinovs, Andris; Bröcker, Lars; Loffhagen, Detlef
    Dielectric-barrier discharges (DBDs) in Ar–N2 mixtures, with N2 fractions in 0.1–1% range, would be attractive alternatives to DBDs in pure N2 if energy-transfer reactions between Ar(1s) atoms and N2 molecules were an efficient source of N atoms. Attempts to functionalize polyolefins in flowing postdischarges fed by such DBDs, as well as the search for the First Positive System in the emission spectrum, however, failed. Evidently, the energy-transfer reactions do not produce N atoms. For Ar(1s3) and Ar(1s5) metastable states, this fact has already been reported in the literature. For Ar(1s2) and Ar(1s4) resonant states, a quantitative argument is derived in this paper: energy transfer from Ar(1s) atoms to N2 molecules is not an efficient source of N atoms.
  • Thumbnail Image
    Item
    Influence of surface parameters on dielectric-barrier discharges in argon at subatmospheric pressure
    (Bristol : IOP Publ., 2020) Stankov, M.; Becker, M.M.; Bansemer, R.; Weltmann, K.-D.; Loffhagen, D.
    The influence of the secondary electron emission coefficient, γ, and the relative permittivity, ɛr, of the dielectric layers on the characteristics of dielectric-barrier discharges (DBDs) is studied by means of numerical modelling and calculated results are compared with experimental data. The analysis has been performed for a geometrically symmetric, plane-parallel DBD in argon with copper electrodes covered by quartz dielectrics. A time-dependent, spatially one-dimensional fluid model involving the drift-diffusion approximation is applied for the numerical analysis of the DBD operating sinusoidally at a frequency of 24 kHz with applied voltages between 1.8 and 3.4 kV and pressures from 100 to 650 mbar. Main features of the model as well as the experimental setup and procedures are given. The modelling studies show especially the sensitivity of the results on the specific choice of γ and ɛr regarding the occurrence and intensity of discharge peaks, the appearance of one or more smaller peaks after the main peak, as well the establishment of a single periodic, multiperiodic or even chaotic temporal evolution of the DBD. In particular, generally good agreement between measured and calculated discharge current signals and the power dissipated in the discharge is found for γ = 0.02 and ɛr = 4.2.