| Popis |
Plasma surface treatments are widely used in various sectors, includingthe polymer industryand decontamination processes. For biobased materials, surface modifications are often required for further processing. However, plasma is rarelyused due to the diverse materials ´ chemical composition and heterogeneous structure, which significantly influencephysics and chemistry within plasma. Moreover, typical atmospheric pressure plasmas are limited in their ability to treat bio-based materials, particularly interms ofspecimen homogeneity, dimensions, tolerances,and stability.Diffuse coplanar surface barrier discharge (DCSBD) plasmaishighly effective for treating large-area flat surfaces. Still, theactive plasma thickness is limited and cannot be applied to 3D structured surfaces. Part of the researchpresents the DCSBD interactions with bio-based materials, such as paper, parchment, leather, and polymers used in librarian practices, restoration, and conservation.The chemical composition changes were studied using various methods, and the inactivation of bacterial contamination was successfully demonstrated. Floating-electrode dielectric barrier discharges (FEDBD) plasmas utilize the workpiece’s surface as intermediate electrodes. However, to date, they cannot treat all bio-based materials without dimensional limitations. In DBDs, high voltage (HV) power supply frequencies range from tens of Hz to hundreds of kHz in ambient air. Continuous DBD at MHz frequencies in ambient air leads to rapid overheating. The solution to overheating is the use of a dual-frequency (DF) HV generator, which allows for the combination of low frequencies (tens of kHz) and high MHz frequencies.In the literature, DF mode was reported to power atmospheric pressure DBDs in, e.g., argon at 13.56 MHz. However, commercially available power supplies do not have sufficient voltage amplitude. Thus, we developed novel resonant MHz transformers suitable for DF applications. When the MHz component is pulsed with a sufficiently low duty cycle, the overheating is rapidly reduced. Thus, the discharge becomes suitable for plasma treatment of various materials.We investigated the DF-DBD behaviour for potential further application in novel material processing. Part of this work presents the interaction of DF-DBD with selected model materials from the classes of metal, glass, ceramic, and polymer. The primary objective was to investigate the working domain of DF-DBD, specifically in terms of discharge gaps, ignition voltage, and the voltage range required for stable generation of DF-DBD, as well as other limitations during interaction with various material classes.
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