Plasma Chemistry and Plasma Processing最新文献

This work investigates the effect of Ar addition on N₂ gliding arc plasma to enhance ammonium ions concentration in water. The concentration of ammonium ion (left({text{N}text{H}}_{4}^{+}right)) increased by 50.2% when Ar gas was added upto 40% by volume to the N₂ gliding arc plasma, thus indicating the significant contribution of Ar in ({text{N}text{H}}_{4}^{+}) synthesis. Adding 20% Ar in N₂ resulted in a maximum ({ text{N}text{H}}_{4}^{+}) concentration of 16.5 ppm and a production rate of 1.31 mg hr^-1. While adding 40% Ar into N₂ plasma, the highest energy efficiency of 0.036 g-({text{N}text{H}}_{4}^{+})KWh⁻¹was obtained with a specific energy input of 742.5 J/L. The mechanisms of ({ text{N}text{H}}_{4}^{+}) enrichment with Ar addition were investigated by studying the electrical properties, vibrational, rotational and electron temperature of the gliding arc plasma with respect to the addition of Ar concentration in N₂ plasma. Results show that the addition of Ar raises the vibrational and electron temperatures, and decreases the rotational temperature of the gliding arc plasma. (As per the reviewer-2 suggestion, this line has been removed from the abstract). Particularly, the presence of 26.5% Ar by volume in N₂ plasma results in a significant ion current, which generates high ionization of ({text{N}}_{2}^{+}).

In this work, we investigate the effect of an external transverse weak magnetic field on the creation of metastable helium atoms and excited helium molecules in a high-voltage pulsed discharge in helium at medium pressure. A two-dimensional fluid model is used to describe a high-voltage pulsed discharge in helium in the external transverse weak magnetic field. The dynamics of discharge development in the high-voltage pulsed discharge in helium at a pressure of 30 Torr in the presence and absence of the magnetic field is studied. The effect of the external magnetic field on the behavior of the density of charged particles, metastable helium atoms, and excited helium molecules in the high-voltage pulsed helium discharge has been investigated. It is shown that in the discharge region, the density of metastable atoms decreases when a transverse magnetic field is applied, which is a consequence of an increase in the frequency of stepwise ionization.

Plasma nitrogen fixation technology is of great significance in solving the problem of nitrogen fertilizer resource shortage, saving energy and reducing carbon emission, promoting sustainable development of agriculture and promoting resource recycling. To enhance the efficiency and treatment capacity of the two-dimensional, blade-type gliding arc nitrogen fixation reaction, a dielectric-boosted gliding arc discharge reactor with a 50-mm-diameter quartz dielectric (DBGAD_Φ50) was used to conduct N₂ fixation into NO_x. The impact of reactor parameters and gas parameters on the nitrogen fixation reaction was systematically investigated in this study. The findings revealed that the DBGAD_Φ50 significantly improved the nitrogen fixation effect. At a specific input energy of 2.7 kJ/L, the concentration of NO_x generated by the dielectric-boosted gliding arc air discharge was 1.12 times that of the conventional gliding arc discharge (GAD). By utilizing the DBGAD_Φ50 reactor, the energy efficiency of 6.83 g/kW h was achieved at a gas flow rate of 5.6 L/min. Appropriately increasing O₂ concentration favors the production of NO_x. In the DBGAD_Φ50, the NO_x concentration was 1.33 times higher than that in the air atmosphere when the added O₂ volume fraction reached 30%. Performance can be further enhanced by adding TiO₂ catalyst particles to the surface of the quartz dielectric to form a catalyst layer approximately 5 mm thick. At an O₂ concentration of 30%, the DBGAD_Φ50 reactor loaded with TiO₂ increased NO_x concentration by 26% and energy efficiency by 49%, respectively, resulting in an efficiency of 14.9 g/kW h compared to the case without catalyst.

The present study demonstrates the successful production of alkaline plasma-activated tap water (PATW), effectively addressing the challenge of acidity in traditional PATW for a range of applications. Through precise control of plasma-forming gases (oxygen, air, argon) and process parameters, particularly by producing PATW under sub-atmospheric pressure conditions, it becomes possible to shift the pH of acidic PATW towards the alkaline range. This transformation enhances its suitability for applications like agriculture, aquaculture, sterilization, wound healing, disinfection, and food preservation, etc.

The investigation encompassed the characterization of plasma and the identification of various plasma species/radicals. The impact of different plasma-forming gases on the pH of PATW and the concentration of reactive species in PATW was thoroughly analyzed. Plasma generated using oxygen and argon resulted in the production of reducing or alkaline PATW, while the use of air and air-argon mixtures led to an acidic or oxidizing nature.

The study also discussed the stability of nitrate ions, nitrite ions, and hydrogen peroxide in PATW, shedding light on their behavior over varying plasma treatment times and plasma-forming gas. Finally, the investigation explored the effects of gas flow rates, gas pressures, water volume, and plasma discharge powers on the concentration of H₂O₂ in PATW, providing valuable insights into optimizing the production process.

The great advantage of plasma technology in harnessing abundant clean energy for electrifying and decentralizing the chemical industry holds the promise of attaining carbon neutrality. Therefore, recent research efforts have been dedicated to reducing the energy costs of plasma processes to facilitate the commercialization of this technology. However, it has been noted an inconsistency in reporting energy costs across the literature resulted from inaccurate estimation of power consumption within the system, leading to the misevaluation of the process, its underlying mechanism, and the significance of critical factors. This study comprehensively addresses these challenges by discussing and refining methods for estimating power consumption in a plasma system. Insights are drawn from our ongoing research in plasma NO_x synthesis, specifically a thorough analysis of the discharge dynamics in a recently developed reactor “high-frequency spark discharge” using a high-speed camera, ICCD camera, and high-performance oscilloscope at various pulse widths of the applied voltage. The investigation revealed the importance of accounting for the post-spark period in the voltage cycle during power estimation, as it demonstrates an influence on NO_x synthesis. Furthermore, the study highlighted and addressed critical errors in power measurement and energy cost estimation in the literature. It is found that a significant error, exceeding ± 70%, arises from overlooking signals delay in the setup and improper adjustment of oscilloscope functions, particularly channel impedance, data averaging, bandwidth, and sampling rate. This paper serves as a valuable guide towards establishing standardized measurements toward the precise estimation of energy costs in plasma processes.