| 1. |
- Baránková, Hana, et al.
(författare)
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Effect of the electrode material on the atmospheric plasma conversion of NO in air mixtures
- 2010
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 84:12, s. 1385-1388
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Tidskriftsartikel (refereegranskat)abstract
- Non-thermal atmospheric pressure plasma is widely used for conversion of hazardous gases. Results from different laboratories confirm importance of energy non-equilibrium in the plasma where dominant energy carriers are electrons and a dominant chemistry is based on formation and interactions of radicals. Because of rather high electric fields required for generation and sustaining of air discharges at atmospheric pressure many plasma systems were found rather to create a lot of NO instead of removing it. A widely supported way to clean NO and NO2 from air mixtures is a plasma assisted catalytic reduction where the cold plasma is combined with the solid-state catalyst. In an ideal case the plasma acts as an oxidation catalyst where an atomic oxygen from air oxidizes NO to NO2 and the solid-state catalysts are then capable to convert all NO2 to N-2 and O-2. In most cases it is also necessary to involve auxiliary gases, e.g., propylene, to make the process efficient enough. This work introduces an original cold plasma system based on atmospheric hollow cathodes generated by a nanopulse DC power with controllable voltage and pulse frequency. The system was optimized in both the geometry and the applied power. However, the material of electrodes was found to be the most important factor affecting the plasma performance and consequently the chemical kinetics. A 100% conversion of NO to NO2 was achieved with a graphite electrode, without using any auxiliary gas and without catalyst. Plasma performance and conversion efficiency are compared for several electrode materials.
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| 2. |
- Söderström, Daniel, 1979-
(författare)
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Modelling and Applications of the Hollow Cathode Plasma
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents experimental and modelling research on atmospheric pressure hollow cathodes and hollow electrodes. Experiments with the hybrid hollow electrode activated discharge (H-HEAD), which is a combination of a hollow cathode and a microwave plasma source, is presented. The experiments show that this source is able to produce long plasma columns in air and nitrogen at atmospheric pressure and at very low gas flow rates. Measurements of the vibrational temperature of the nitrogen molecules are also presented in this thesis. The vibrational temperature is an indication of the electron temperature in the plasma, an important characteristic of the plasma. Modelling work on the hollow cathode at atmospheric pressure with fluid equations is also presented. It is shown that the inclusion of fast and secondary electrons, characteristic of the hollow cathode plasmas, increases the sheath width. The sheath width was found to be of the order of 100 μm. By modelling the plasma as highly collisional by using the drift-diffusion approximation, it was shown that the increase in sheath thickness was larger at lower pressures than at higher pressures. Still, the sheath width can be of the order of 100 μm. A pulsed atmospheric plasma in a hollow electrode geometry was also modelled by the drift-diffusion fluid equations, with the addition of the energy equation for electrons. Rate and transport coefficients for the electrons were calculated from the solution to the Boltzmann equation as functions of mean electron energy. The dynamics of the plasma at pulse rise time showed large electron density and mean energy peaks at the cathode ends, but also that these quantities were enhanced at the centre of the discharge, between the cathode plates.
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| 3. |
- Barankova, Hana, et al.
(författare)
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Abnormal High Rate Deposition of TiN Films by the Radio Frequency Plasma Jet System
- 1995
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Ingår i: J Electrochem Soc. - 0013-4651. ; 142:3, s. 883-887
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency Ar and Ar + N-2 plasma jets generated in a hollow electrode terminated by a small size Ti nozzle were used for deposition of Ti and TiN films. The regime with low content of reactive gas resulted in an extreme enhancement of TiN deposition
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| 4. |
- Barankova, Hana, et al.
(författare)
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Amorphous Carbon Coatings on Glass for High Voltage Protection
- 2022
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Ingår i: ECS Journal of Solid State Science and Technology. - : The Electrochemical Society. - 2162-8769 .- 2162-8777. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency Hollow Cathode based hybrid process integrating both Physical Vapor Deposition and Plasma Enhanced Chemical Vapor Deposition was used for deposition of amorphous carbon on glass samples. The films were subjected to high voltage pulses and the performance was compared with uncoated glass samples to test the protection ability of the films, the ability to prevent the deteriorating effects of corona flashovers/arcs. In contrast to the uncoated glass the well adherent carbon films with thicknesses between 3.5 and 17 mu m exhibited an excellent protection of the glass substrate against the flashovers/arc damages in both polarities of the electric field with voltages up to 300 kV.
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| 5. |
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| 6. |
- Barankova, Hana, et al.
(författare)
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Characterization of the linear arc discharge (LAD) source for film deposition
- 1997
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Ingår i: SURFACE & COATINGS TECHNOLOGY. - 0257-8972. ; 94-5:1-3, s. 578-582
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Tidskriftsartikel (refereegranskat)abstract
- The linear arc discharge (LAD) source is a parallel plate hollow cathode with a magnetic field perpendicular to the plates near the outlet slit of the cathode. The hollers cathode discharge is generated by radio frequency (rf) power and is confined mainly
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| 7. |
- Barankova, Hana, et al.
(författare)
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Cold atmospheric plasma sources
- 2002
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Ingår i: INVITED PAPER, ANZIO 2002, 5th Symp.Europ.Vac.Coaters, September 30, Rome-Anzio, Italy, abstract only.
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Konferensbidrag (refereegranskat)
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| 8. |
- Barankova, Hana, et al.
(författare)
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Cold atmospheric plasma sources based on hollow cathodes
- 2002
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Ingår i: INVITED presentation at 1st Topical Meeting on Pulsed and Atmospheric Pressure Plasma Processing, FMT - Forschungszentrum für Mikrostrukturtechnik, Univestity of Wuppertal, Wuppertal, March 2002.
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Konferensbidrag (refereegranskat)
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| 9. |
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| 10. |
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