| 1. |
- Ahmed, Naeem, et al.
(författare)
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Effects of Oxygen (O2) Plasma Treatment in Promoting the Germination and Growth of Chili
- 2022
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Ingår i: Plasma chemistry and plasma processing. - : Springer. - 0272-4324 .- 1572-8986. ; 42:1, s. 91-108
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Tidskriftsartikel (refereegranskat)abstract
- In general, seed germination is improved by low-pressure plasma treatment using precursors such as air, nitrogen, O2, and argon, etc. For the first time, low-pressure O2 plasma was used to treat chili seeds in this study. When compared to untreated and vacuum-treated seeds, O2 plasma treatment using the discharge power of 80 W for 60 s significantly improves chili seed germination and growth. The effect of vacuum on the germination and growth of chili seeds was also studied and shown to be negligible. The physical and chemical changes induced by O2 plasma treatment were investigated to understand the plasma treatment to germination improvement. Combinatory etching and chemical modification aided imbibition and increased germination percentage in this O2 plasma treatment on chili seeds. The success of this method has the potential to be scaled up to solve food security issues with seeds that would otherwise struggle to germinate.
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| 2. |
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| 3. |
- Bardos, Ladislav, et al.
(författare)
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Production of Hydrogen-Rich Synthesis Gas by Pulsed Atmospheric Plasma Submerged in Mixture of Water with Ethanol
- 2017
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Ingår i: Plasma chemistry and plasma processing. - : Springer Science and Business Media LLC. - 0272-4324 .- 1572-8986. ; 37:1, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen-rich synthesis gas was produced by pulsed dc plasma submerged into ethanol-water mixtures using an original system with a coaxial geometry. The ignition of the discharge is immediately followed by production of hydrogen and after a short time necessary for filling the outlet tubing a flame can be ignited. No auxiliary gas was used for the reforming process. The synthesis gas containing up to 60% of hydrogen was formed, at the outflow rate of 250 sccm at the average power as low as 10 W. The hydrogen production efficiency corresponds to 12 kWh/kg H-2.
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| 4. |
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| 5. |
- Chazelas, Christophe, et al.
(författare)
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Main issues for a fully predictive plasma spray torch model and numerical considerations
- 2017
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Ingår i: Plasma chemistry and plasma processing. - : Springer Science and Business Media LLC. - 0272-4324 .- 1572-8986. ; 37:3, s. 627-651
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Tidskriftsartikel (refereegranskat)abstract
- Plasma spray is one of the most versatile and established techniques for the deposition of thick coatings that provide functional surfaces to protect or improve the performance of the substrate material. However, a greater understanding of plasma spray torch operation will result in improved control of process and coating properties and in the development of novel plasma spray processes and applications. The operation of plasma torches is controlled by coupled dynamic, thermal, chemical, electromagnetic, and acoustic phenomena that take place at different time and space scales. Computational modeling makes it possible to gain important insight into torch characteristics that are not practically accessible to experimental observations, such as the dynamics of the arc inside the plasma torch. This article describes the current main issues in carrying out plasma spray torch numerical simulations at a high level of fidelity. These issues encompass the use of non-chemical and non-thermodynamic equilibrium models, incorporation of electrodes with sheath models in the computational domain, and resolution of rapid transient events, including the so-called arc reattachment process. Practical considerations regarding model implementation are also discussed, particularly the need for the model to naturally reproduce the observed torch operation modes in terms of voltage and pressure fluctuations.
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| 6. |
- Gao, Jinlong, et al.
(författare)
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In-Situ Non-intrusive Diagnostics of Toluene Removal by a Gliding Arc Discharge Using Planar Laser-Induced Fluorescence
- 2017
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Ingår i: Plasma Chemistry and Plasma Processing. - : Springer Science and Business Media LLC. - 0272-4324 .- 1572-8986. ; 37:2, s. 433-450
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Tidskriftsartikel (refereegranskat)abstract
- A non-equilibrium gliding arc discharge anchored on two diverging stainless steel electrodes was extended into open air by a toluene-containing air jet. The removal process of the toluene by the non-equilibrium gliding arc discharge was investigated through in situ and non-intrusive laser-based techniques. Simultaneous planar laser-induced fluorescence (PLIF) of toluene and OH radicals were employed to achieve on-line visualization of the toluene decomposing process by the gliding arc discharge column. Toluene PLIF images with high spatial and temporal resolution showed that the non-equilibrium plasma of the gliding arc discharge is effective in decomposing toluene molecules. Instantaneous toluene removal efficiency was estimated from the toluene PLIF images, showing that the initial toluene concentrations and oxygen concentrations affected the toluene removal efficiency. The toluene removal efficiency decreased with the initial toluene concentration, whereas the efficiency increased with the oxygen concentration. The OH generation in the discharge was found to be enhanced with an increase of the toluene concentration from the OH PLIF results. The relative instantaneous distribution between the OH produced from the discharge channels and the toluene flow was simultaneously visualized. The instantaneous distributions of toluene and OH radicals that were acquired simultaneously by PLIF, were well complementary, suggesting that radicals generated by the gliding arc discharge were responsible for toluene removal in the active volume of the gliding arc discharge. The effective width of the plasma volume for the toluene removal were measured, which gives a new insight into the optimization of industrial design for practical gliding arc reactors.
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| 7. |
- Rosen, Johanna, et al.
(författare)
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Effect of ion energy on structure and composition of cathodic arc deposited alumina thin films
- 2005
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Ingår i: Plasma chemistry and plasma processing. - : Springer Science Business Media. - 0272-4324 .- 1572-8986. ; 25:4, s. 303-317
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Tidskriftsartikel (refereegranskat)abstract
- The effect of energy supplied to the growing alumina film on the composition and structure has been investigated by varying substrate temperature and substrate bias potential. The constitution and composition were studied by X-ray diffraction and elastic recoil detection analysis, respectively. Increasing the substrate bias potential from -50 to -100 V caused the amorphous or weakly crystalline films to evolve into stoichiometric, crystalline films with a mixture of the alpha- and gamma-phase above 700 degrees C, and. gamma-phase dominated films at temperatures as low as 200 degrees C. All films had a grain size of less than 10 nm. The combined constitution and grain size data is consistent with previous work stating that. - alumina is thermodynamically stable at grain sizes less than 12 nm [McHale et al., Science 277, 788 ( 1997)]. In order to correlate phase formation with synthesis conditions, the plasma chemistry and ion energy distributions were measured at synthesis conditions. These results indicate that for a substrate bias potential of - 50V, ion energies in excess of 100 eV are attained, both from a high energy tail and the accelerated ions with charge greater than 1. These results are of importance for an increased understanding of the evolution of film composition and microstructure, also providing a pathway to. - alumina growth at temperatures as low as 200 degrees C.
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| 8. |
- Rosen, Johanna, et al.
(författare)
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Influence of gas entry point on plasma chemistry, ion energy and deposited alumina thin films in filtered cathodic arc
- 2007
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Ingår i: Plasma chemistry and plasma processing. - : Springer Science Business Media. - 0272-4324 .- 1572-8986. ; 27:5, s. 599-608
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Tidskriftsartikel (refereegranskat)abstract
- The effect of gas entry point on the plasma chemistry, ion energy distributions and resulting alumina thin film growth have been investigated for a d.c. cathodic arc with an aluminum cathode operated in an oxygen/argon atmosphere. Ions of aluminum, oxygen and argon, as well as ions originating from the residual gas are investigated, and measurements for gas entry at both the cathode and close to the substrate are compared. The latter was shown to result in higher ion flux, lower levels of ionised residual gas, and lower ion energies, as compared to gas inlet at the cathode. These plasma conditions that apply when gas entry at the substrate is used result in a higher film deposition rate, less residual gas incorporation, and more stoichiometric alumina films. The results show that the choice of gas entry point is a crucial parameter in thin film growth using reactive PVD processes such as reactive cathodic arc deposition.
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