Probing the impact of oxygen negative ions on the self-organized pattern in 1 atm DC glow with liquid anode

Journal Article · Wed Jan 29 00:00:00 EST 2025 · Plasma Sources Science and Technology

DOI:https://doi.org/10.1088/1361-6595/adac0a· OSTI ID:2520537

Yang, Zimu ^[1]; Yatom, Shurik ^[2]; Foster, John E. ^[1]

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1. Univ. of Michigan, Ann Arbor, MI (United States)
2. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

In an atmospheric DC glow discharge with a liquid anode, the plasma anode glow attached to the grounded liquid surface under certain conditions self-organizes into coherent patterns. Optical emission spectroscopy revealed that the emission consists primarily of the second positive system of nitrogen, N₂(C-B), whose excitation energy is low and sensitive to changes in the electron energy distribution. In addition to electrons, negative ions can accumulate in the anode sheath and affect the local space charge. It has been speculated that these negative ions play a role in pattern formation at the anode surface. In this work, the role of oxygen negative ions was explored. It was found that the formation of anode patterns requires at least a 7% volume fraction of oxygen in the ambient gas. Results showed that O₂^- is the dominant negative ion species in atmospheric DC glow discharge, with a density of ~10¹² cm^-3. While the presence of oxygen appears to be crucial for pattern formation, this study indicated that patterns still formed without geometric changes even when 62% of negative ions in the plasma were detached by a laser. This suggests that negative ions do not support the patterns, while oxygen's heating effect may induce instability at the anode.

• Research Organization: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• Grant/Contract Number: AC02-09CH11466; SC0024538
• OSTI ID: 2520537
• Alternate ID(s): OSTI ID: 2504023
• Journal Information: Plasma Sources Science and Technology, Journal Name: Plasma Sources Science and Technology Vol. 34; ISSN 0963-0252
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY