Optical diagnostics of a gliding arc.

Area of Science:

• Plasma Physics
• Chemical Physics
• Fluid Dynamics

Background:

• Gliding arc discharges are utilized in various applications, including pollution control and materials processing.
• Understanding the dynamic behavior of these plasmas is crucial for optimizing their performance.
• Previous studies often lacked detailed temporal and spatial resolution of the plasma's life cycle.

Purpose of the Study:

• To investigate the dynamic processes of gliding arc plasma in ambient air.
• To characterize the temporal evolution and spatial distribution of plasma species.
• To correlate plasma behavior with the driving AC voltage parameters.

Main Methods:

• Utilized high-speed imaging (tens to hundreds of kHz) to capture plasma dynamics.
• Employed spatially and temporally resolved optical emission spectroscopy.
• Applied planar laser-induced fluorescence (PLIF) for ground-state OH radical imaging.

Main Results:

• Observed distinct life cycle phases: ignition, motion, pulsation, short-cutting, and extinction.
• Detected plasma emission pulsation at 62.5 kHz (twice the AC supply frequency).
• Identified excited N2, NO, and OH radicals, with intensities varying by position and AC phase.
• PLIF revealed high OH radical concentrations in the plasma periphery, not the core.

Conclusions:

• Gliding arc plasma exhibits complex, cyclical dynamics influenced by the AC power supply.
• The formation of ground-state OH radicals occurs predominantly outside the central plasma column.
• These findings provide insights into plasma chemistry and dynamics for targeted applications.