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Abstract Pattern formation in plasma–solid interaction represents a great research challenge in many applications from plasma etching to surface treatment, whereby plasma attachments on electrodes (arc roots) are constricted to self-organized spots. Gliding arc discharge in a Jacob’s Ladder, exhibiting hopping dynamics, provides a unique window to probe the nature of pattern formation in plasma–surface interactions. In this work, we find that the existence of negative differential resistance (NDR) across the sheath is responsible for the observed hopping pattern. Due to NDR, the current density and potential drop behave as activator and inhibitor, the dynamic interactions of which govern the surface current density re-distribution and the formation of structured spots. In gliding arc discharges, new arc roots can form separately in front of the existing root(s), which happens periodically to constitute the stepwise hopping. From the instability phase-diagram analysis, the phenomenon that arc attachments tend to constrict itself spontaneously in the NDR regime is well explained. Furthermore, we demonstrate via a comprehensive magnetohydrodynamics (MHD) computation that the existence of a sheath NDR can successfully reproduce the arc hopping as observed in experiments. Therefore, this work uncovers the essential role of sheath NDR in the plasma–solid surface pattern formation and opens up a hitherto unexplored area of research for manipulating the plasma–solid interactions.
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Scaling Up of Non-Thermal Gliding Arc Plasma Systems for Industrial Applications
Scaling up of transitional “warm” plasmas to industrial level gives possibility to develop plasma systems that combine advantages of thermal and non thermal discharges such as low temperature and high process selectivity (compare to thermal plasma) at high pressure and average power density. Non-equilibrium “cold” gliding arcs (with observation of equilibrium to non equilibrium transition) has been demonstrated at power level 2–3 kW and proved to be a highly efficient plasma stimulators of several plasma chemical and plasma catalytic processes, including hydrogen/syngas generation from biomass, coal and organic wastes, exhaust gas cleaning, fuel desulfurization and water cleaning from emerging contaminants. The gliding arc evolution includes initial micro-arc phase with fast transition to transient non-equilibrium phase with elevated electric field, low gas and high electron temperatures, as well as selective generation of active species typical for cold plasmas. The paper will describe experimentally achieved scaling up of the non-equilibrium gliding arc discharges to the level of 10–15 kW, as well as theoretical scaling up limitations of this powerful non-equilibrium plasma systems.
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- Award ID(s):
- 1747671
- PAR ID:
- 10313082
- Date Published:
- Journal Name:
- Plasma chemistry and plasma processing
- ISSN:
- 1572-8986
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/https://doi.org/10.1007/s11090-021-10203-5
