Nonthermal plasma

A nonthermal plasma, cold plasma or non-equilibrium plasma is a plasma which is not in thermodynamic equilibrium, because the electron temperature is much hotter than the temperature of heavy species (ions and neutrals). As only electrons are thermalized, their Maxwell-Boltzmann velocity distribution is very different from the ion velocity distribution.^[1] When one of the velocities of a species does not follow a Maxwell-Boltzmann distribution, the plasma is said to be non-Maxwellian.

A kind of common nonthermal plasma is the mercury-vapor gas within a fluorescent lamp, where the "electron gas" reaches a temperature of 20,000 K (19,700 °C; 35,500 °F) while the rest of the gas, ions and neutral atoms, stays barely above room temperature, so the bulb can even be touched with hands while operating.

Applications

Food industry

In the context of food processing, a nonthermal plasma (NTP) or cold plasma is specifically an antimicrobial treatment being investigated for application to fruits, vegetables and meat products with fragile surfaces.^[2] These foods are either not adequately sanitized or are otherwise unsuitable for treatment with chemicals, heat or other conventional food processing tools. While the applications of nonthermal plasma were initially focused on microbiological disinfection,^[3] newer applications such as enzyme inactivation, biomolecule oxidation, protein modification, prodrug activation, and pesticide dissipation are being actively researched. ^{[4][5][6] [7]} Nonthermal plasma also sees increasing use in the sterilization of teeth^[8][9] and hands,^[10] in hand dryers^[11] as well as in self-decontaminating filters.^[12]

The term cold plasma has been recently used as a convenient descriptor to distinguish the one-atmosphere, near room temperature plasma discharges from other plasmas, operating at hundreds or thousands of degrees above ambient (see Plasma (physics) § Temperature. Within the context of food processing the term "cold" can potentially engender misleading images of refrigeration requirements as a part of the plasma treatment. However, in practice this confusion has not been an issue. "Cold plasmas" may also loosely refer to weakly ionized gases (degree of ionization < 0.01%).

Nomenclature

The nomenclature for nonthermal plasma found in the scientific literature is varied. In some cases, the plasma is referred to by the specific technology used to generate it ("gliding arc", "plasma pencil", "plasma needle", "plasma jet", "dielectric barrier discharge", "piezoelectric direct discharge plasma", etc.), while other names are more generally descriptive, based on the characteristics of the plasma generated ("one atmosphere uniform glow discharge plasma", "atmospheric plasma", "ambient pressure nonthermal discharges", "non-equilibrium atmospheric pressure plasmas", etc.). The two features which distinguish NTP from other mature, industrially applied plasma technologies, is that they are 1) nonthermal and 2) operate at or near atmospheric pressure.

Technologies

	NTP technology class
	I. Remote treatment	II. Direct treatment	III. Electrode contact
Nature of NTP applied	Decaying plasma (afterglow) - longer lived chemical species	Active plasma - short and long-lived species	Active plasma - all chemical species, including shortest lived and ion bombardment
NTP density and energy	Moderate density - target remote from electrodes. However, a larger volume of NTP can be generated using multiple electrodes	Higher density - target in the direct path of a flow of active NTP	Highest density - target within NTP generation field
Spacing of target from NTP-generating electrode	Approx. 5–20 cm; arcing (filamentous discharge) unlikely to contact target at any power setting	Approx. 1–5 cm; arcing can occur at higher power settings, can contact target	Approx. ≤ 1 cm; arcing can occur between electrodes and target at higher power settings
Electrical conduction through target	No	Not under normal operation, but possible during arcing	Yes, if target is used as an electrode OR if target between mounted electrodes is electrically conductive
Suitability for irregular surfaces	High - remote nature of NTP generation means maximum flexibility of application of NTP afterglow stream	Moderately high - NTP is conveyed to target in a directional manner, requiring either rotation of target or multiple NTP emitters	Moderately low - close spacing is required to maintain NTP uniformity. However, electrodes can be shaped to fit a defined, consistent surface.
Examples of technologies	Remote exposure reactor, plasma pencil	Gliding arc; plasma needle; microwave-induced plasma tube	Parallel plate reactor; needle-plate reactor; resistive barrier discharge; dielectric barrier discharge
References	[13][14][15]	[16][17][18][19][20]	[21][22][23][24][17][18]

Medicine

Main article: Plasma medicine

An emerging field adds the capabilities of nonthermal plasma to dentistry and medicine. Cold plasma is used to treat chronic wounds.^[25]

Power generation

Main article: Magnetohydrodynamic generator

See also: Electrothermal instability

Magnetohydrodynamic power generation, a direct energy conversion method from a hot gas in motion within a magnetic field was developed in the 1960s and 1970s with pulsed MHD generators known as shock tubes, using non-equilibrium plasmas seeded with alkali metal vapors (like caesium, to increase the limited electrical conductivity of gases) heated at a limited temperature of 2000 to 4000 kelvins (to protect walls from thermal erosion) but where electrons were heated at more than 10,000 kelvins.^{[26][27][28][29]}

A particular and unusual case of "inverse" nonthermal plasma is the very high temperature plasma produced by the Z machine, where ions are much hotter than electrons.^[30][31]

Aerospace

Main article: Magnetohydrodynamic converter

See also: Paschen's law

Aerodynamic active flow control solutions involving technological nonthermal weakly ionized plasmas for subsonic, supersonic and hypersonic flight are being studied, as plasma actuators in the field of electrohydrodynamics, and as magnetohydrodynamic converters when magnetic fields are also involved.^[32]

Studies conducted in wind tunnels involve most of the time low atmospheric pressure similar to an altitude of 20–50 km, typical of hypersonic flight, where the electrical conductivity of air is higher, hence non-thermal weakly ionized plasmas can be easily produced with a fewer energy expense.^{[citation needed]}

Catalysis

Atmospheric pressure non-thermal plasma can be used to promote chemical reactions. Collisions between hot temperature electrons and cold gas molecules can lead to dissociation reactions and the subsequent formation of radicals. This kind of discharge exhibits reacting properties that are usually seen in high temperature discharge systems.^[33] Non-thermal plasma is also used in conjunction with a catalyst to further enhance the chemical conversion of reactants or to alter the products chemical composition.

Among the different application fields, there are ozone production^[34] at a commercial level; pollution abatement, both solid (PM, VOC) and gaseous (SOx, NOx);^[35] CO₂ conversion^[36] in fuels (methanol, syngas) or value added chemicals; nitrogen fixation; methanol synthesis; liquid fuels synthesis from lighter hydrocarbons (e.g. methane),^[37] hydrogen production via hydrocarbons reforming^[38]

Configurations

The coupling between the two different mechanisms can be done in two different ways: two-stage configuration, also called post-plasma catalysis (PPC) and one-stage configuration, also called in-plasma catalysis (IPC) or plasma enhanced catalysis (PEC).

In the first case the catalytic reactor is placed after the plasma chamber. This means that only the long-lived species can reach the catalyst surface and react, while short-lived radicals, ions and excited species decay in the first part of the reactor. As an example, the oxygen ground state atom O(3P) has a lifetime of about 14 μs^[39] in a dry air atmospheric pressure plasma. This means that only a small region of the catalyst is in contact with active radicals. In a such two-stage set-up, the main role of the plasma is to alter the gas composition fed to the catalytic reactor.^[40] In a PEC system, synergistic effects are greater since short-lived excited species are formed near the catalyst surface.^[41] The way the catalyst is inserted in the PEC reactor influence the overall performance. It can be placed inside the reactor in different ways: in powder form (packed bed), deposited on foams, deposited on structured material (honeycomb), and coating of the reactor walls

Packed bed plasma-catalytic reactor are commonly used for fundamental studies^[33] and a scale-up to industrial applications is difficult since the pressure drop increase with the flow rate.

Plasma-catalysis interactions

In a PEC system, the way the catalyst is positioned in relation to the plasma can affect the process in different ways. The catalyst can positively influence the plasma and vice versa resulting in an output that cannot be obtained using each process individually. The synergy that is established is ascribed to different cross effects. ^{[42] [43] [38] [44] [45]}

• Plasma effects on catalyst:
  • Change in the physiochemical properties. Plasma change the adsorption/desorption equilibrium on the catalyst surface leading to higher adsorption capabilities. An interpretation to this phenomenon is not yet clear.^[46]
  • Higher catalyst surface area. A catalyst exposed to a discharge can give rise to the formation of nanoparticles.^[47] The higher surface/volume ratio leads to better catalyst performances.
  • Higher adsorption probability.
  • Change in the catalyst oxidation state. Some metallic catalyst (e.g. Ni, Fe) are more active in their metallic form. The presence of a plasma discharge can induce a reduction of the catalyst metal oxides, improving the catalytic activity.
  • Reduced coke formation. When dealing with hydrocarbons, coke formation leads to a progressive deactivation of the catalyst.^[48] The reduced coke formation in presence of plasma reduces the poisoning/deactivation rate and thus extending the life of a catalyst.
  • Presence of new gas phase species. In a plasma discharge a wide range of new species is produced allowing the catalyst to be exposed to them. Ions, vibrationally and rotationally excited species do not affect the catalyst since they lose charge and the additional energy they possess when they reach a solid surface. Radicals, instead, show high sticking coefficients for chemisorption, increasing the catalytic activity.

• Catalyst effects on plasma:
  • Local electric field enhancement. This aspect is mainly related to a packed-bed PEC configuration. The presence of a packing material inside an electric field generates local field enhancements due to the presence of asperities, solid material surface inhomogeneities, presence of pores and other physical aspects. This phenomenon is related to surface charge accumulation on the packing material surface and it is present even if a packed-bed is used without a catalyst. Despite this is a physical aspect, it also affects the chemistry since it alters the electron energy distribution in proximity of the asperities.
  • Discharges formation inside pores. This aspect is strictly related to the previous one. Small void spaces inside a packing material affect the electric field strength. The enhancement can also lead to a change in the discharge characteristics, which can be different from the discharge condition of the bulk region (i.e. far from the solid material).^[49] The high intensity of the electric field can also lead to the production of different species that are not observed in the bulk.
  • Change in the discharge type. Inserting a dielectric material in a discharge region leads to a shifting in the discharge type. From a filamentary regime a mixed filamentary/surface discharge is established. Ions, excited species and radicals are formed in a wider region if a surface discharge regime is present.^[50]

Catalyst effects on plasma are mostly related to the presence of a dielectric material inside the discharge region and do not necessarily require the presence of a catalyst.

See also

• Anisothermal plasma
• Gliding Arc Plasmatron^[51]

References

1. von Engel, A. and Cozens, J.R. (1976) "Flame Plasma" in Advances in electronics and electron physics, L. L. Marton (ed.), Academic Press, ISBN 978-0-12-014520-1, p. 99 Archived 2 December 2016 at the Wayback Machine
2. "Decontamination of Fresh Production with Cold Plasma". U.S. Department of Agriculture. Retrieved 2006-07-28.
3. Laroussi, M. (1996). “Sterilization of Contaminated Matter by an Atmospheric Pressure Plasma”, IEEE Trans. Plasma Sci. 34, 1188 – 1191.
4. Ahmadi, Mohsen; Nasri, Zahra; von Woedtke, Thomas; Wende, Kristian (2022). "d-Glucose Oxidation by Cold Atmospheric Plasma-Induced Reactive Species". ACS Omega. 7 (36): 31983–31998. doi:10.1021/acsomega.2c02965. PMC 9475618. PMID 36119990.
5. Nasri, Zahra; Memari, Seyedali; Wenske, Sebastian; Clemen, Ramona; Martens, Ulrike; Delcea, Mihaela; Bekeschus, Sander; Weltmann, Klaus-Dieter; Woedtke, Thomas; Wende, Kristian (2021). "Singlet-Oxygen-Induced Phospholipase A2 Inhibition: A Major Role for Interfacial Tryptophan Dioxidation". Chemistry – A European Journal. 27 (59): 14702–14710. doi:10.1002/chem.202102306. PMC 8596696. PMID 34375468.
6. Wende, K.; Nasri, Z.; Striesow, J.; Ravandeh, M.; Weltmann, K.-D.; Bekeschus, S.; Woedtke, T. von (2022). "Is Biomolecule Oxidation by Plasma-Derived Reactive Species Restricted to the Gas-Liquid Interphase?". 2022 IEEE International Conference on Plasma Science (ICOPS). pp. 1–2. doi:10.1109/ICOPS45751.2022.9813129. ISBN 978-1-6654-7925-7. S2CID 250318321. Retrieved 2022-07-01.
7. Ahmadi, Mohsen; Potlitz, Felix; Link, Andreas; von Woedtke, Thomas; Nasri, Zahra; Wende, Kristian (2022). "Flucytosine-based prodrug activation by cold physical plasma". Archiv der Pharmazie. 355 (9): e2200061. doi:10.1002/ardp.202200061. PMID 35621706. S2CID 249095233.
8. "Plasma rips away tenacious tooth bacteria". 2009-06-11. Retrieved 2009-06-20.
9. Beth Dunham (June 5, 2009). "Cool plasma packs heat against biofilm". Archived from the original on June 18, 2009. Retrieved 2009-06-20.
10. Eisenberg, Anne (2010-02-13). "Hospital-Clean Hands, Without All the Scrubbing". The New York Times. Retrieved 2011-02-28.
11. "American Dryer UK Set To Transform Hand Hygiene With Pioneering 'Germ Destroying'". Bloomberg. 2015-03-27. Archived from the original on 2015-04-03.
12. Kuznetsov, I.A.; Saveliev, A.V.; Rasipuram, S.; Kuznetsov, A.V.; Brown, A.; Jasper, W. (2012). Development of Active Porous Medium Filters Based on Plasma Textiles. Porous Media and Its Applications in Science, Engineering and Industry, AIP Conf. Proc. 1453. AIP Conference Proceedings. Vol. 1453. pp. 265–270. Bibcode:2012AIPC.1453..265K. doi:10.1063/1.4711186.
13. Gadri, Rami Ben; Roth, J.Reece; Montie, Thomas C.; Kelly-Wintenberg, Kimberly; Tsai, Peter P.-Y.; Helfritch, Dennis J.; Feldman, Paul; Sherman, Daniel M.; Karakaya, Fuat; Chen, Zhiyu (2000). "Sterilization and plasma processing of room temperature surfaces with a one atmosphere uniform glow discharge plasma (OAUGDP)". Surface and Coatings Technology. 131 (1–3). Elsevier BV: 528–541. doi:10.1016/s0257-8972(00)00803-3. ISSN 0257-8972.
14. Laroussi, M.; Lu, X. (2005-09-12). "Room-temperature atmospheric pressure plasma plume for biomedical applications". Applied Physics Letters. 87 (11). AIP Publishing: 113902. Bibcode:2005ApPhL..87k3902L. doi:10.1063/1.2045549. ISSN 0003-6951.
15. Montie, T.C.; Kelly-Wintenberg, K.; Roth, J.R. (2000). "An overview of research using the one atmosphere uniform glow discharge plasma (OAUGDP) for sterilization of surfaces and materials". IEEE Transactions on Plasma Science. 28 (1). Institute of Electrical and Electronics Engineers (IEEE): 41–50. Bibcode:2000ITPS...28...41M. doi:10.1109/27.842860. ISSN 0093-3813.
16. Lee, Kwon-Yong; Joo Park, Bong; Hee Lee, Dong; Lee, In-Seop; O. Hyun, Soon; Chung, Kie-Hyung; Park, Jong-Chul (2005). "Sterilization of Escherichia coli and MRSA using microwave-induced argon plasma at atmospheric pressure". Surface and Coatings Technology. 193 (1–3). Elsevier BV: 35–38. doi:10.1016/j.surfcoat.2004.07.034. ISSN 0257-8972.
17. Niemira et al., 2005. P2. IFT NPD Mtg., Wyndmoor, Pennsylvania
18. NIemira et al., 2005. P2-40. IAFP Mtg., Baltimore, Maryland
19. Sladek, R E J; Stoffels, E (2005-05-20). "Deactivation ofEscherichia coliby the plasma needle". Journal of Physics D: Applied Physics. 38 (11). IOP Publishing: 1716–1721. Bibcode:2005JPhD...38.1716S. doi:10.1088/0022-3727/38/11/012. ISSN 0022-3727. S2CID 95924351.
20. Stoffels, E; Flikweert, A J; Stoffels, W W; Kroesen, G M W (2002-08-30). "Plasma needle: a non-destructive atmospheric plasma source for fine surface treatment of (bio)materials". Plasma Sources Science and Technology. 11 (4). IOP Publishing: 383–388. Bibcode:2002PSST...11..383S. doi:10.1088/0963-0252/11/4/304. ISSN 0963-0252. S2CID 250895777.
21. Deng et al., 2005. Paper #056149, ASAE Ann. Mtg., Tampa, Florida
22. Kelly-Wintenberg, K.; Hodge, Amanda; Montie, T. C.; Deleanu, Liliana; Sherman, Daniel; Reece Roth, J.; Tsai, Peter; Wadsworth, Larry (1999). "Use of a one atmosphere uniform glow discharge plasma to kill a broad spectrum of microorganisms". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 17 (4). American Vacuum Society: 1539–1544. Bibcode:1999JVSTA..17.1539K. doi:10.1116/1.581849. ISSN 0734-2101.
23. Laroussi, M; Mendis, D A; Rosenberg, M (2003-04-30). "Plasma interaction with microbes". New Journal of Physics. 5 (1). IOP Publishing: 41. Bibcode:2003NJPh....5...41L. doi:10.1088/1367-2630/5/1/341. ISSN 1367-2630.
24. Montenegro, J.; Ruan, R.; Ma, H.; Chen, P. (2002). "Inactivation of E. coli O157:H7 Using a Pulsed Nonthermal Plasma System". Journal of Food Science. 67 (2). Wiley: 646–648. doi:10.1111/j.1365-2621.2002.tb10653.x. ISSN 0022-1147.
25. Abu Rached, Nessr; Kley, Susanne; Storck, Martin; Meyer, Thomas; Stücker, Markus (January 2023). "Cold Plasma Therapy in Chronic Wounds—A Multicenter, Randomized Controlled Clinical Trial (Plasma on Chronic Wounds for Epidermal Regeneration Study): Preliminary Results". Journal of Clinical Medicine. 12 (15): 5121. doi:10.3390/jcm12155121. ISSN 2077-0383. PMC 10419810. PMID 37568525.
26. Kerrebrock, Jack L.; Hoffman, Myron A. (June 1964). "Non-Equilibrium Ionization Due to Electron Heating. Theory and Experiments" (PDF). AIAA Journal. 2 (6): 1072–1087. Bibcode:1964AIAAJ...2.1080H. doi:10.2514/3.2497. Archived from the original (PDF) on 2019-08-19. Retrieved 2018-04-10.
27. Sherman, A. (September 1966). "MHD Channel Flow with Non-Equilibrium lonization" (PDF). The Physics of Fluids. 9 (9): 1782–1787. Bibcode:1966PhFl....9.1782S. doi:10.1063/1.1761933. Archived from the original (PDF) on 2018-04-12. Retrieved 2018-04-10.
28. Argyropoulos, G. S.; Demetriades, S. T.; Kentig, A. P. (1967). "Current Distribution in Non-Equilibrium J×B Devices" (PDF). Journal of Applied Physics. 38 (13): 5233–5239. Bibcode:1967JAP....38.5233A. doi:10.1063/1.1709306.
29. Zauderer, B.; Tate, E. (September 1968). "Electrical characteristics of a linear, nonequilibrium, MHD generator" (PDF). AIAA Journal. 6 (9): 1683–1694. Bibcode:1968AIAAJ...6.1685T. doi:10.2514/3.4846.
30. Haines, M. G.; LePell, P. D.; Coverdale, C. A.; Jones, B.; Deeney, C.; Apruzese, J. P. (23 February 2006). "Ion Viscous Heating in a Magnetohydrodynamically Unstable Pinch at Over 2 × 10⁹ Kelvin" (PDF). Physical Review Letters. 96 (7): 075003. Bibcode:2006PhRvL..96g5003H. doi:10.1103/PhysRevLett.96.075003. PMID 16606100.
31. Petit, J.-P. "The Z Machine: Over two billion degrees! Malcolm Haines' paper" (PDF). Retrieved 2018-04-07.
32. Weier, Tom; Shatrov, Victor; Gerbeth, Gunter (2007). "Flow Control and Propulsion in Poor Conductors". In Molokov, Sergei S.; Moreau, R.; Moffatt, H. Keith (eds.). Magnetohydrodynamics: Historical Evolution and Trends. Springer Science+Business Media. pp. 295–312. doi:10.1007/978-1-4020-4833-3. ISBN 978-1-4020-4832-6.
33. Whitehead, J Christopher (22 June 2016). "Plasma–catalysis: the known knowns, the known unknowns and the unknown unknowns". Journal of Physics D: Applied Physics. 49 (24): 243001. Bibcode:2016JPhD...49x3001W. doi:10.1088/0022-3727/49/24/243001. S2CID 101887286.
34. Eliasson, B; Hirth, M; Kogelschatz, U (14 November 1987). "Ozone synthesis from oxygen in dielectric barrier discharges". Journal of Physics D: Applied Physics. 20 (11): 1421–1437. Bibcode:1987JPhD...20.1421E. doi:10.1088/0022-3727/20/11/010. S2CID 250811914.
35. Chang, Jen-Shih (December 2001). "Recent development of plasma pollution control technology: a critical review". Science and Technology of Advanced Materials. 2 (3–4): 571–576. Bibcode:2001STAdM...2..571C. doi:10.1016/S1468-6996(01)00139-5.
36. Ashford, Bryony; Tu, Xin (February 2017). "Non-thermal plasma technology for the conversion of CO 2". Current Opinion in Green and Sustainable Chemistry. 3: 45–49. doi:10.1016/j.cogsc.2016.12.001.
37. De Bie, Christophe; Verheyde, Bert; Martens, Tom; van Dijk, Jan; Paulussen, Sabine; Bogaerts, Annemie (23 November 2011). "Fluid Modeling of the Conversion of Methane into Higher Hydrocarbons in an Atmospheric Pressure Dielectric Barrier Discharge". Plasma Processes and Polymers. 8 (11): 1033–1058. doi:10.1002/ppap.201100027.
38. CHEN, H; LEE, H; CHEN, S; CHAO, Y; CHANG, M (17 December 2008). "Review of plasma catalysis on hydrocarbon reforming for hydrogen production—Interaction, integration, and prospects". Applied Catalysis B: Environmental. 85 (1–2): 1–9. doi:10.1016/j.apcatb.2008.06.021.
39. Holzer, F (September 2002). "Combination of non-thermal plasma and heterogeneous catalysis for oxidation of volatile organic compounds Part 1. Accessibility of the intra-particle volume". Applied Catalysis B: Environmental. 38 (3): 163–181. doi:10.1016/S0926-3373(02)00040-1.
40. Neyts, E C; Bogaerts, A (4 June 2014). "Understanding plasma catalysis through modelling and simulation—a review". Journal of Physics D: Applied Physics. 47 (22): 224010. Bibcode:2014JPhD...47v4010N. doi:10.1088/0022-3727/47/22/224010. S2CID 120159417.
41. Harling, Alice M.; Glover, David J.; Whitehead, J. Christopher; Zhang, Kui (July 2009). "The role of ozone in the plasma-catalytic destruction of environmental pollutants". Applied Catalysis B: Environmental. 90 (1–2): 157–161. doi:10.1016/j.apcatb.2009.03.005.
42. Neyts, E C; Bogaerts, A (4 June 2014). "Understanding plasma catalysis through modelling and simulation—a review". Journal of Physics D: Applied Physics. 47 (22): 224010. Bibcode:2014JPhD...47v4010N. doi:10.1088/0022-3727/47/22/224010. S2CID 120159417.
43. Chen, Hsin Liang; Lee, How Ming; Chen, Shiaw Huei; Chang, Moo Been; Yu, Sheng Jen; Li, Shou Nan (April 2009). "Removal of Volatile Organic Compounds by Single-Stage and Two-Stage Plasma Catalysis Systems: A Review of the Performance Enhancement Mechanisms, Current Status, and Suitable Applications". Environmental Science & Technology. 43 (7): 2216–2227. Bibcode:2009EnST...43.2216C. doi:10.1021/es802679b. PMID 19452866.
44. Van Durme, Jim; Dewulf, Jo; Leys, Christophe; Van Langenhove, Herman (February 2008). "Combining non-thermal plasma with heterogeneous catalysis in waste gas treatment: A review". Applied Catalysis B: Environmental. 78 (3–4): 324–333. doi:10.1016/j.apcatb.2007.09.035. hdl:1854/LU-419124.
45. Vandenbroucke, Arne M.; Morent, Rino; De Geyter, Nathalie; Leys, Christophe (November 2011). "Non-thermal plasmas for non-catalytic and catalytic VOC abatement". Journal of Hazardous Materials. 195: 30–54. doi:10.1016/j.jhazmat.2011.08.060. PMID 21924828.
46. Blin-Simiand, Nicole; Tardiveau, Pierre; Risacher, Aurore; Jorand, François; Pasquiers, Stéphane (31 March 2005). "Removal of 2-Heptanone by Dielectric Barrier Discharges – The Effect of a Catalyst Support". Plasma Processes and Polymers. 2 (3): 256–262. doi:10.1002/ppap.200400088.
47. Hong, Jingping; Chu, Wei; Chernavskii, Petr A.; Khodakov, Andrei Y. (7 July 2010). "Cobalt species and cobalt-support interaction in glow discharge plasma-assisted Fischer–Tropsch catalysts". Journal of Catalysis. 273 (1): 9–17. doi:10.1016/j.jcat.2010.04.015.
48. Beuther, H.; Larson, O.A.; Perrotta, A.J. (1980). The Mechanism of Coke Formation on Catalysts. Studies in Surface Science and Catalysis. Vol. 6. pp. 271–282. doi:10.1016/s0167-2991(08)65236-2. ISBN 9780444419200. {{cite book}}: |journal= ignored (help)
49. Zhang, Yu-Ru; Van Laer, Koen; Neyts, Erik C.; Bogaerts, Annemie (May 2016). "Can plasma be formed in catalyst pores? A modeling investigation". Applied Catalysis B: Environmental. 185: 56–67. doi:10.1016/j.apcatb.2015.12.009. hdl:10067/1298080151162165141.
50. Bednar, Nikola; Matović, Jovan; Stojanović, Goran (December 2013). "Properties of surface dielectric barrier discharge plasma generator for fabrication of nanomaterials". Journal of Electrostatics. 71 (6): 1068–1075. doi:10.1016/j.elstat.2013.10.010.
51. Ramakers, M; Trenchev, G; Heijkers, S; Wang, W; Bogaerts, A (2017). "Gliding Arc Plasmatron: Providing an Alternative Method for Carbon Dioxide Conversion". ChemSusChem. 10 (12): 2642–2652. Bibcode:2017ChSCh..10.2642R. doi:10.1002/cssc.201700589. hdl:10067/1441840151162165141. PMID 28481058.