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Published on: November 3, 2016
Probing instabilities in arc plasma devices using binary gas mixtures
S Ghorui1, M Vysohlid, J V R Heberlein
1Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Summary
Instabilities in arc plasma devices originate from the anode wall boundary layer, not the core flow. Arc current, not flow rate, dictates instability behavior, revealing new insights into plasma dynamics.
Area of Science:
- Plasma Physics
- Fluid Dynamics
- Electrical Engineering
Background:
- Arc plasma devices are crucial in various industrial applications.
- Understanding plasma instabilities is key to optimizing device performance and preventing failures.
- Current models struggle to fully explain observed instability phenomena in binary gas arcs.
Purpose of the Study:
- To experimentally identify the root causes of instabilities in arc plasma devices.
- To investigate the role of gas mixtures, specifically argon-hydrogen, in plasma instabilities.
- To challenge existing theories by exploring the influence of boundary layers versus core flow.
Main Methods:
- Utilized the demixing phenomena in arcs to study instability characteristics.
- Employed an experimental approach with argon as the primary gas and hydrogen as a secondary gas.
- Analyzed the influence of arc current and flow rates on instability behavior in frequency space.
Main Results:
- Identified the anode wall boundary layer, particularly the anodic arc root, as the primary source of instabilities.
- Demonstrated that bulk core flow has a negligible impact on these instabilities.
- Found that arc current, not flow rate, is the dominant factor controlling instability behavior.
- Observed distinct modes of instability: steady, takeover, and restrike.
Conclusions:
- Arc plasma instabilities are predominantly governed by conditions at the anode boundary layer.
- The findings necessitate a revision of current theoretical models for arc plasma stability.
- The study highlights the critical role of arc current in controlling plasma dynamics and suggests potential for improved device control.
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