Splashing of tungsten-based anode during arc discharge

Area of Science:

• Materials Science
• Plasma Physics
• Surface Science

Background:

• Arc discharge is crucial in various industrial applications.
• Understanding anode erosion mechanisms is vital for process control and material longevity.
• Tungsten-based anodes are common in high-temperature plasma applications.

Purpose of the Study:

• To elucidate the unique mechanism of splashing from a tungsten-based anode during arc discharge.
• To identify the role of additives and electromagnetic forces in anode splashing.
• To characterize the physical processes leading to droplet ejection.

Main Methods:

• Observation of splashing during arc discharge with a tungsten-based anode.
• High-speed imaging to capture luminescence and surface dynamics.
• Temperature measurements of the anode surface.
• Energy dispersive spectrometry (EDS) mapping for elemental analysis.

Main Results:

• A novel splashing mechanism involving liquid metal column breakoff was identified.
• Blue-violet luminescence from cerium ions preceded concavity formation.
• Anode surface temperatures exceeded additive boiling points during splashing.
• Measured droplet speeds indicated significant electromagnetic force contribution.
• EDS confirmed residual additives on the anode post-discharge.

Conclusions:

• Anode splashing is initiated by additive bubble formation and bursting at temperatures above their boiling point.
• A micro-plasma jet is generated, leading to liquid column elongation and breakoff.
• Electromagnetic forces drive high-speed droplet ejection, contributing to anode erosion.
• The findings provide critical insights into arc discharge material transport phenomena.