For the first time, results are presented demonstrating the feasibility of carbon dioxide disposal while simultaneously producing syngas using a microwave discharge in liquid methanol, with CO2 bubbling at atmospheric pressure. The CO2 input flow rate ranged from 100 to 700 mL/min, and the incident microwave power varied between 450 and 540 W. The main discharge products were H2 and CO. The highest degree of carbon dioxide decomposition was 75%.
Cold Atmospheric Plasma (CAP) is gaining interest as a biomedical technology due to its ability to modulate cellular behaviour through the controlled delivery of reactive oxygen and nitrogen species (RONS), UV photons, and electric fields. This is particularly relevant to wound healing, where redox modulation can reduce microbial burden and promote tissue repair. Mesenchymal stem/stromal cells (MSCs) are key regulators of immune response and tissue regeneration, suggesting potential synergy between CAP and MSC-based approaches. However, before CAP can be incorporated into MSC-based approaches, it is essential to establish whether it compromises core MSC characteristics. This study investigated the effects of CAP on MSC viability, morphology, phenotype and multilineage differentiation potential. Adipose-derived immortalised MSCs were exposed to CAP using a helium plasma jet under optimised conditions and assessed for up to 72 h. CAP exposure produced treatment-time-dependent effects on metabolic activity and morphology, enabling the identification of a non-cytotoxic treatment window. Under mild conditions, CAP-treated MSCs maintained the characteristic MSC phenotype (CD73-, CD90-, and CD105-positive; HLA-DR- negative) and retained adipogenic, osteogenic, and chondrogenic differentiation capacity. These findings indicate that controlled CAP exposure preserves key MSC properties, supporting further investigation of CAP as a complementary tool for MSC-based wound healing applications.
At present, one of the key challenges in the development of controlled thermonuclear fusion (CTF) facilities is to ensure stable auxiliary plasma heating to the parameters required to sustain long-duration, high-power discharges. To achieve such operating regimes in tokamaks, reliable operation of ion-cyclotron resonance heating (ICRH) systems is required. These systems must be capable of efficiently transferring megawatt-level radio-frequency (RF) power to the plasma under substantially varying load conditions. Of particular importance is the commissioning of high-power RF generators, since tuning and impedance-matching errors can result in damage to expensive equipment and significantly increase the time required to prepare for experimental campaigns. Despite considerable experience in the application of ion-cyclotron resonance heating (ICRH) systems at tokamak facilities worldwide, the testing and commissioning of high-power triode-based generators using load equivalents remain relevant for each specific system. This is due, among other factors, to the individual characteristics of the antenna–feeder path, matching devices, and generator specifications. For the KTM tokamak, this task is of particular importance because commissioning of the ICRH system is a prerequisite for achieving the plasma parameters required to investigate the behaviour of promising candidate materials for the first wall and divertor under conditions as close as possible to those expected in future fusion reactors. In this work, an active load equivalent based on an aqueous saline solution was developed and used to experimentally test a high-frequency generator based on GU-98AM triodes operating in push–pull mode. The generator was tested at a reduced anode voltage of up to 5 kV, with stable RF generation at 13.1 MHz and RF power transfer of up to approximately 20 kW to the active load equivalent. These results demonstrate the applicability of the developed active load equivalent for preliminary tuning and testing of the RF generator and antenna–feeder system. The obtained results are limited to the reduced-voltage and reduced-power conditions investigated in this study and do not represent validation at the nominal anode voltage of 18 kV and rated RF power of 2 MW.
A nonlinear plasma-dynamic model has been proposed to describe the formation of nano-hillocks on the yttrium iron garnet surface due to the bombardment of energetic C60 ions. Localized energy deposition is thought to generate a transient multicomponent plasma, described in the framework of the multi-fluid model and eventually reduced to the Gardner equation by means of the reductive perturbation technique. Unlike the traditional electrostatic analysis, the model proposed in this paper connects the Gardner solution with measurable parameters of the surface, which provides a possibility to interpret the amplitude and spatial scale of the Gardner solution as the height and width of the nano-hillocks. The results obtained turn out to be in agreement with the observed morphology, indicating that the Gardner nonlinear evolution can be applied to the real spatial characteristics of the nanostructure obtained as a result of the irradiation. The reductive-perturbation derivation of a Gardner equation is a standard nonlinear-plasma procedure and is not claimed here as the principal novelty. The new step is the dimensional mapping of the Gardner solitary-wave solution to the measured nano-hillock morphology and its quantitative comparison with the digitized scanning-force-microscopy profile. The plasma-dynamic interpretation is conditional: the Gardner reduction is applied only after the prompt electronic cascade, and its validity requires the remaining source/sink, charge-changing, and heavy-particle collisional times to be longer than the nonlinear evolution time.
Atmospheric-pressure nonequilibrium argon plasmas are used in many applications, and their electron properties may depend on the device configuration. Here, the electron temperature and density of two devices of contrasting geometry, a closed flow-channel type dielectric barrier discharge (DBD) and an open-air tube-type plasma jet, were determined from continuum optical emission spectra. The electron energy distribution function was represented by a two-temperature model combining a Druyvesteynian bulk component, which contains the great majority of the electrons, and a Maxwellian tail component, which is a small high-energy minority, with all parameters obtained by an exhaustive grid search. Introducing the tail component reduced the fitting residual by more than two orders of magnitude, supporting a two-component parameterization of the time-averaged distribution. The bulk temperature remained within 0.35–0.42 eV for every condition in which the two-component model was applicable, whereas the electron density spanned six orders of magnitude, from 6.6×1016 cm−3 in the DBD to 5.5×1010 cm−3 in the jet plume; at the same monitored power of 12 W, the DBD was about ten times denser. The continuum constrains only about 1% of the electrons, those above the photon-energy threshold, so the total density is a model-dependent extrapolation. Two checks that do not use the continuum, a Stark-broadening estimate and a collisional-radiative analysis of the line spectra, are both incompatible with the extrapolated total: inserting it into the collisional-radiative model overestimates the measured line emission by five to seven orders of magnitude, while the line spectra themselves require a density of order 1014 cm−3. The two methods do not, however, reproduce each other’s dependence on the operating condition. Within the continuum analysis, the device configuration therefore governs the density, whereas the bulk temperature is comparatively insensitive to geometry.
