The aim of the study was to develop an indirect calibration methodology to quantify the gas temperature in an encased dielectric barrier discharge (DBD) reactor using a two-stage coupled thermal–fluid simulation in COMSOL Multiphysics. Sinusoidal and sub-microsecond pulsed waveforms were compared at 7 and 8.5 kV. The conductivity of the plasma region (σplasma) was calibrated from the experimentally measured power consumption (Pexp) to determine the volumetric heat source (Qavg,vol), which was used to calculate the simulated power consumption Psim. The calibration yielded a Psim–Pexp error within 0.5
Protective oils and oxide films are frequently present on cast-iron tooling and can compromise early-stage surface activation during plasma nitriding. Here, gray and ductile cast irons were intentionally soiled with two industrial protective oils and pre-oxidized either by controlled furnace exposure or by water exposure to reproduce mixed organic and inorganic contamination states. TGA/DTG of the oils informed a staged heating profile to limit abrupt outgassing and avoid uncontrolled cracking with carbonaceous redeposition. Three in-chamber plasma-cleaning routes were integrated with a fixed nitriding cycle without breaking vacuum: CN1 (80
The use of cold atmospheric plasma in agriculture is limited due to its potential toxic effect. The properties of cold plasma and its effect on plants can vary depending on the type of device used, treatment conditions, and the physiological characteristics of the treated object. This study provides a comparative analysis of the growth and physiological parameters of Hordeum vulgare L. seedlings after root and leaf treatment with cold atmospheric plasma. Using hyperspectral technology, infrared spectroscopy, and fluorescence imaging, it was shown that 1 s plasma exposure (generated by a coaxial system with a dielectric barrier discharge, a power of 40 W, and Ar flow rate of 142 L/h) of the roots increased leaf reflectance, transpiration and CO2 assimilation rates, while photosynthetic electron flows remained unchanged. These seedlings showed enhanced dry matter content and primary leaf length compared to control plants. Foliar treatment of Hordeum vulgare L. seedlings with the same plasma did not affect stomatal conductance, but increased chlorophyll and carotenoid content, activated cyclic electron transport around photosystem I, and enhanced the proton gradient across the thylakoid membrane. With this type of plasma impact, increased leaf length was recorded 3 days after treatment. The obtained data demonstrated the growth-promoting effect of cold atmospheric plasma using the tested treatment methods.
The concentration of alkaline-earth metal ions in aqueous solutions is measured using the method of atmospheric pressure discharge plasma emission spectroscopy with a liquid cathode. Rubidium atoms added as RbCl serve as the actinometer component in the plasma. A known concentration of this reference cation is added to the analyzed solution. Magnesium, calcium, and barium chloride solutions with concentrations ranging from 10− 4 to 0.1 g/L are analyzed. It is demonstrated that the addition of background electrolytes to the solution affects the emission intensity of the metal atomic lines. However, using the ratio of the emission intensity of the analyzed component to that of the actinometer component effectively compensates for this matrix effect, ensuring accurate quantitative analysis.
Graphene and other sp2-hybridized carbon nanostructures are highly sought for their large surface area, novel electrical and optical properties, and potential applications for energy conversion/storage. Atmospheric pressure plasmas offer a scalable route to carbon nanoparticle synthesis, but controlling the carbon allotrope formation is a major challenge because methane plasmas can lead to a large variety of non-graphitic nanostructures such as amorphous carbon nanospheres. Here we report on a gas flow-and-composition-based selectivity window for few-layer-graphene synthesis using an atmospheric pressure radiofrequency plasma reactor. Our key finding is that selecting for wrinkled few-layer graphene nanoparticle formation as opposed to other allotropes of carbon nanoparticles can be achieved by solely adjusting methane concentration and flowrate. This result establishes that atmospheric pressure plasmas can go beyond general carbon nanoparticle synthesis and enable selective control over allotrope formation.
