Surface dielectric barrier discharge (SDBD) is used in a variety of different applications; however, the ozone generated in the discharge can be toxic to people in the vicinity. In this paper, we study the SDBD (using generators with smooth-edge, serrated and thin-wire high-voltage electrodes) in terms of ozone generation. The electrical measurements and the time-resolved plasma imaging revealed differences in the discharge current, dissipated power and plasma morphology for the different types of SDBD generators and showed significant suppression of the streamer formation from the thin-wire electrode. We determined the amount of ozone produced by each generator and found that despite the observed differences in discharge between the generators, the ozone production yield and the maximum volumetric concentration of ozone for all three generators is a linear function of only one parameter—the discharge active power. We also found that the ozone production efficiency of 9.66 g/kWh is constant for all three generators. Our results show that SDBD generators can be safely used in the enclosed space if the SDBD discharge operates with relatively low active power (the SDBD generator working with the active power of 1.7 W did not exceed the ozone concentration of 0.1 ppm in the 60 m³ room).

Ice accumulation on wind turbine blades due to the impact of supercooled water droplets can be reduced by the application of surfaces with anti-icing properties. Hydrophobic surfaces are considered as a promising solution because of their water repellent behavior. In recent years, short-pulsed laser technologies have been developed as an efficient technique to modify the surface properties of materials. However, the anti-icing properties of such surfaces have not yet been validated. In this work, a hybrid modification of polyester resin-based gelcoats was adopted. Laser patterning (LP) was used to produce periodic surface structures on modified unsaturated polyester resin (UPR) substrates. One of the innovations of this research is the utilization of novel purpose-made chemical modifiers for gelcoats. The implementation of linear polymethylhydrosiloxane (PMHS) as a building block is a key improvement in terms of durability and functionality of the coating, since there is an option of introducing not only groups bonding in the polyester into one molecule, but also groups that increase hydrophobicity. The other novelty is a successfully conducted experiment combining such chemical modification with laser texturization of the surface. The influence of the laser energy, pattern shape, and spatial periods on the topographical characteristics and hydrophobicity as well as the anti-icing properties of the produced surfaces were investigated. To characterize the surface topography of the produced structures, scanning electron microscopy (SEM) and profilometer were utilized. Measurements of the wettability parameters (static contact angle and contact angle hysteresis) on the treated surfaces allowed the identification of the influence of wetting behavior and laser parameters on the investigated materials. Anti-icing properties were characterized by ice adhesion (IA) and freezing delay time (FDT) tests. It was found that hybrid modification of unsaturated polyester resin by chemical modifiers and laser treatment increased the hydrophobic and anti-icing properties of polyester gelcoats.

One of the most commonly applied methods of joining dissimilar materials is gluing. This could be mainly attributed to the applicability of this technique in various industries. The article presents a method of material surface treatment, which increases the shear strength of adhesive joints for lightweight metals such as aluminum with plastics. For this purpose, laser surface microstructuring was performed on each of the selected construction materials. As a result of the performed treatment, the active surface of the glued area was increased, which increased the adhesive strength. The picosecond laser with UV radiation used in the research is TruMicro 5325c with which material can be removed as a result of the cold ablation phenomenon. The applied parameters of the laser device did not cause thermal damage to the surface of the microstructured materials, which was confirmed by microscopic examination. Laser micromachining did not deteriorate the degree of wetting of the tested materials, either, as was confirmed by the contact angle and surface energy measurements with the use of water as the measuring liquid. In investigated cases of microstructure types, the presented method significantly increased the shear strength of the joints formed, as demonstrated by the presented strength test results. Research has shown that created joints with microstructure made according to the described method, are characterized by a significant increase in strength, up to 376%, compared to materials without microstructure. The presented results are part of a series of tests aimed at selecting the operating laser parameters for the implementation of geometric shapes of microstructures which will increase the strength of adhesive joints in selected materials.

We characterized non-thermal plasma generated in two types of Surface Dielectric Barrier Discharge (SDBD) reactors, one with a planar and the other with a cylindrical electrode. Plasma was examined using the time-resolved imaging and Optical Emission Spectroscopy (OES) methods. We observed that the cylindrical electrode suppresses plasma formation during both discharge modes: positive streamers and pseudo-Trichel microdischarges. The propagation velocity of the plasma front was estimated to be in the range 12–15 m/s, regardless of the discharge mode and electrode type. Spectral analysis showed that the plasma emission spectrum consisted mainly of the first and second positive nitrogen bands. Using Specair software, we calculated the plasma thermodynamic parameters and found that, despite morphological differences, the plasma generated in both reactors had similar thermodynamic properties. Finally, we discussed the temporal evolution of the discharge and attributed the plasma suppression caused by the cylindrical electrode to the characteristic uniformity of the electric field around and along this electrode.

In this paper, an experimental investigation of the ablation plasma generated from the copper substrate by means of nanosecond laser pulses is presented. We studied the evolution of the ablation plasma in the first 1000 ns after plasma onset using the fast-gated imaging and optical emission spectroscopy methods. Plasma imaging showed that the expansion of the plume front can be described using a so-called drag model, with the expansion limit increasing with laser fluence from 254 µm for 30 J / c m 2 to 375 µm for 67 J / c m 2 . By using the Boltzmann plot and Stark broadening methods, it was found that within the first microsecond after onset, the electron excitation temperature and electron number density decrease from 1.2 eV to 0.8 eV and from 4 × 1 0 16 c m − 3 to 5 × 1 0 15 c m − 3 , respectively. Using the McWhirter criterion, we confirmed that in the considered time range the plasma remains in a state of local thermodynamic equilibrium.