Barrier discharges (BDs) can be operated in so-called diffuse modes. In contrast to the usual filamentary regime, which is characterized by a large number of individual microdischarges, the plasma of a diffuse BD covers the entire electrode area uniformly. Depending on the operation conditions (gas composition, amplitude and frequency of applied voltage), different diffuse modes can be investigated, namely, the atmospheric pressure Townsend discharge (APTD) and the atmospheric pressure glow discharge (APGD). The subject of the paper is the study of the transition between APTD and APGD as well as between diffuse and filamentary BD modes. Therefore, BDs were studied in the gas mixtures N2/H2, N2/He, N2/Ne and N2/Ar. It is shown that APGD in the noble gases helium and neon is formed due to high ionization rate at a comparatively low electric field, assisted by indirect ionization mechanisms involving metastable states of inert gases and nitrogen impurities, while the existence of APTD is coupled to the existence of metastable states of molecular nitrogen. Furthermore, a similar memory effect of residual surface charges on the dielectric barriers as described for filamentary BDs was observed in diffuse BDs.

The atmospheric pressure glow discharge burning in nitrogen with small admixture of organosilicon compounds such as hexamethyldisilazane or hexamethyldisiloxane was used for the deposition of thin organosilicon polymer films. The properties of the discharge were studied by means of optical emission spectroscopy and electrical measurements. The deposited films were characterized by atomic force microscopy, x-ray photoelectron spectroscopy, infrared transmission measurements, ellipsometry, depth sensing indentation technique and contact angle measurements. The films were polymer-like, transparent in the visible range, with uniform thickness and without pinholes. The film hardness varied from 0.3 to 0.6 GPa depending on deposition conditions, the elastic modulus was in the range 15–28 GPa and the surface free energy was in the range 26–45 mJ m−2. The studied films exhibited good adhesion to the substrate.

The dielectric barrier discharge burning at atmospheric pressure usually has a filamentary non-homogeneous form. However, it was found that uniform dielectric barrier discharge can be generated in helium, nitrogen and in the mixture of argon with acetone under specific conditions. Such uniform discharge is called atmospheric pressure glow discharge (APGD). We studied dielectric barrier discharge burning in neon at atmospheric pressure and we found that the APGD can also be generated in neon. We measured the electrical characteristics of APGD in neon for different voltages and frequencies of power supply and different gas flows. We found that higher gas flow stabilizes the APGD and we determined the area of parameters in which the APGD burns. The images of discharges were recorded by a video camera and emission optical spectra were measured by a spectrometer. The properties of the discharges in neon were compared with the properties of discharges burning in argon and in the mixture of neon with argon.

Diffuse dielectric barrier discharges in neon and helium at atmospheric pressure were studied. The discharges were generated between two metal electrodes, both covered by an alumina layer and driven by ac voltage of frequency 10 kHz. The discharge gap was 2.2 mm and 5 mm, respectively. The discharges were investigated by electrical measurements and by temporally and spatially resolved optical emission spectroscopy. The experimental results revealed similar discharge behaviour in both gases being considered. Although the discharges were ignited at slightly different electric field strengths, their evolutions were found to be similar. At maximum discharge current the spatial light intensity distribution was characterized by the formation of a cathode fall. A difference was observed in the magnitudes of the current density only. In addition to the regime with a single discharge pulse per voltage half period T /2, a discharge mode with two and more subsequent current pulses per T /2 (also referred to as the pseudoglow discharge regime in the literature) was obtained due to an increase in the voltage amplitude or an admixture of nitrogen.

To cite this version:DAbstract. The atmospheric pressure dielectric barrier discharge burning in nitrogen with small admixture of hexamethyldisiloxane (HMDSO) was used for the deposition of thin organosilicon films. The thin films were deposited on glass, silicon and polycarbonate substrates, the substrate temperature during the deposition process was elevated up to values within the range 25 • C -150 • C in order to obtain hard SiO x -like thin films. The properties of the discharge were studied by means of optical emission spectroscopy and electrical measurements. The deposited films were characterised by Rutherford backscattering and elastic recoil detection methods, x-ray photoelectron spectroscopy, infrared spectroscopy measurements, ellipsometry and depth sensing indentation technique. It was found that the films properties depend significantly on substrate temperature at deposition. An increase of substrate temperature from 25 • C to 150 • C leads to an increase of film hardness from 0.4 GPa to 7 GPa and the film chemical composition changes from CH x Si y O z to SiO x H y . The films were transparent in visible range.