Coupling Cold Plasma Research Articles

RF-transpond: A 1D coupled cold plasma wave and plasma transport model for ponderomotive force driven density modification parallel to B0

The RF-Transpond code couples a fluid plasma transport solver with a frequency domain cold plasma RF wave solver in a 1D domain parallel to a strong background magnetic field. A ponderomotive force term proportional to parallel gradients in the electric field strength is included in the transport model in order to describe ponderomotive effects in the scrape-off layer (SOL) of fusion plasmas. The transport and wave codes are verified independently and a coupled case corresponding to experimental parameters from the LArge Plasma Device (LAPD) is presented. The density perturbation ratio Rn, calculated to describe ponderomotive force driven modifications, is up to 20% for the simulation inputs used. Program summaryProgram Title: rf-transpondCPC Library link to program files:https://doi.org/10.17632/xn3y2yx9wj.1Developer's repository link:https://github.com/rhealbarnett/rf-transpond.gitLicensing provisions: MITProgramming language: MatlabNature of problem: Self consistent coupled model describing ponderomotive force driven density modification in the near field of RF antennas.Solution method: The density and velocity solutions are calculated from the continuity and momentum transport equations, solved using a finite difference time domain method, which include a ponderomotive force term that depends on the radio frequency electric field. The frequency domain electric field solution is calculated from the cold plasma wave equation, solved using a finite difference frequency domain method, where the cold plasma dielectric tensor is a function of the density. The electric field and density couple the two models, providing self consistency.

Employing one-step coupling cold plasma and thermal polymerization approach to construct nitrogen defect-rich carbon nitrides toward efficient visible-light-driven hydrogen generation

Construction of structural defects in photocatalysts is a powerful tool for regulating their photocatalytic performance. In this work, we develop a facile one-step coupling cold plasma and thermal polymerization approach to synthesize a series of nitrogen defect-rich graphitic carbon nitrides (C3N4-x), which are used for visible-light-driven hydrogen generation from water. The nitrogen defect-induced band structure regulation of C3N4-x catalysts can be carried out through controlling the bombardment time and excitation power of generator during the plasma modification process. The defective C3N4-x catalysts have the extended visible light absorption and improved separation efficiency of photogenerated charge carriers, which results in the boosted hydrogen generation activity. Particularly, the optimal C3N4-x possesses a hydrogen generation rate of 2.46 mmol h−1 g−1, which is about 4.5 times higher than the pristine C3N4 synthesized by the single thermal polymerization of urea. The cold plasma modification-based one-step synthesis approach guides us for rationally designing defective nanomaterials with excellent catalytic performance.

Coupling cold plasma and membrane photobioreactor for enhanced fouling control during livestock excreta treatment

To treat high-turbidity livestock excrements (LE), this study suggests a synergistic system coupling cold plasma (CP) and membrane photobioreactor (MPBR). During the continuous operation of the integrated system, physico-chemical oxidation of CP decompose turbidity and total suspended solids (TSS) up to 99.9%. The microalgal concentration of Scenedesmus obliquus in the following MPBR reach as high as 1,944 mg D.W./L, which indicates the residual organic and inorganic substances were actively consumed by phototrophic metabolism. Pearson correlation analysis confirms this synergistic relationship of turbidity and TSS with biological growth parameters such as biomass growth, soluble microbial products, and extracellular polymeric substances. Results evidence that the turbidity and TSS are directly connected to the microalgal growth in this integrated system thus the role of CP is crucial to achieving the LE treatment goal. Overall, this study provides a guideline to support the enhanced treatment strategy to control LE with the production of bioresources for sustainable carbon and nutrient cycles.

Features and application of coupled cold plasma and photocatalysis processes for decontamination of water

Dielectric barrier discharge plasma and photocatalysis have been proposed as tools for decontamination of process water, especially in food industry. The present investigation aims to redefine and identify the features of coupling the two technologies in terms of degradation efficiency of a model compound. Results show that, when the process is carried out in plasma activated water in the presence of irradiated TiO2, the efficiency of the integrated process is lower than the sum of the two processes acting separately. It is proposed that afterglow species, e.g. hydrogen peroxide and/or peroxynitrites could be activated by UVA light irradiation producing hydroxyl radicals in the liquid phase. Even if TiO2 limits this additional effect by acting as UVA screen barrier material, its decontamination efficiency under certain conditions results higher than that obtained with plasma systems. These results open the route to chlorine-free decontamination processes and redefine the application framework of this integrated approach.

Effect of Cold Plasma Treatment on Electrospun Nanofibers Properties: A Review.

Electrospinning of polymer materials is a widely used technique, providing nanofibrous mats with high surface to volume ratio and porosity, which show a great interest in many fields such as biomedical applications. However, nanofibers generally present some weakness including low mechanical resistance, poor bioactivity, or lower biocompatibility. Among the surface modification techniques described in the literature, cold plasma treatment may prevent these drawbacks and especially improve properties of electrospun nanofibers. Therefore, this review lays out the state-of-the-art of cold plasma treatment of nanofibers and, especially, its effect on the biocompatibility improvement, the immobilization/adsorption of molecules of interest, the surface grafting/cross-linking, and the use of the modified nanofibers in biomedical applications. In particular, this literature review demonstrates the positive effect of cold plasma treatment onto the mechanical, biological, or chemical properties of nanofibers. Future investigations should go further on the effects of the gas type but also on the possibility of coupling cold plasma treatment with other surface modification techniques.

ENHANCEMENT OF NUCLEAR FUSION IN A STRONGLY COUPLED COLD PLASMA

It is pointed out that enhancement of nuclear fusion in a strongly coupled cold plasma can be realized in laboratory condition.