Spatiotemporally resolved characteristics of a gliding arc discharge in a turbulent air flow at atmospheric pressure

Abstract

A gliding arc discharge was generated in a turbulent air flow at atmospheric pressure driven by a 35 kHz alternating current (AC) electric power. The spatiotemporally resolved characteristics of the gliding arc discharge, including glow-type discharges, spark-type discharges, short-cutting events and transitions among the different types of discharges, were investigated using simultaneously optical and electrical diagnostics. The glow-type discharge shows sinusoidal-like voltage and current waveforms with a peak current of hundreds of milliamperes. The frequency of the emission intensity variation of the glow-type discharge is the same as that of the electronic power dissipated in the plasma column. The glow-type discharge can transfer into a spark discharge characterized by a sharp peak current of several amperes and a sudden increase of the brightness in the plasma column. Transitions can also be found to take place from spark-type discharges to glow-type discharges. Short-cutting events were often observed as the intermediate states formed during the spark-glow transition. Three different types of short-cutting events have been observed to generate new current paths between two plasma channel segments, and between two electrodes, as well as between the channel segment and the electrodes, respectively. The short-cut upper part of the plasma column that was found to have no current passing through can be detected several hundreds of microseconds after the short-cutting event. The voltage recovery rate, the period of AC voltage-driving signal, the flow rates and the rated input powers were found to play an important role in affecting the transitions among the different types of discharges.

Translational, rotational, vibrational and electron temperatures of a gliding arc discharge

“…The electrodes are made of stainless steel tubes with an outer diameter of 3 mm that were cooled internally by water. A similar gliding arc discharge system has been described in our previous work [4,37,44,45]. An air flow was fed through a 3 mm-diameter circular nozzle between the two electrodes to extend the plasma column in an upward direction.…”

“…The air flow rate was controlled at 17.5 standard liter per minute (SLM) by a mass flow controller. At this input power and flow rate, the glowtype discharge dominates whereas the spark-type discharges can be just identified occasionally [37,44]. In this work, temperatures of the glow-type discharge are measured due to the fact that the glow-type discharges can be dominantly observed at 17.5 SLM and 800 W. In addition, the glow-type discharges are more likely to be captured by a lowfrequency laser (10 Hz) used in the Rayleigh measurements.…”

“…In addition, the electron temperature can be calculated using the reduced electric field strength that is dependent on simultaneous measurements of both the electric field strength and the translational temperature. In our earlier work, an AC gliding arc discharge was generated in atmospheric air, and temporally [37,44], spatially [45] and spectrally [38] resolved characteristics of the gliding arc discharge in atmospheric air were experimentally investigated. Glow-type and spark-type discharges can be recognized during the evolution of the gliding arc discharge [37,44].…”

“…In our earlier work, an AC gliding arc discharge was generated in atmospheric air, and temporally [37,44], spatially [45] and spectrally [38] resolved characteristics of the gliding arc discharge in atmospheric air were experimentally investigated. Glow-type and spark-type discharges can be recognized during the evolution of the gliding arc discharge [37,44]. The glow-type discharges are characterized by current peaks of hundreds of milliamperes whereas the spark-type discharges are recognized by current spikes of up to tens of amperes [44].…”

“…Glow-type and spark-type discharges can be recognized during the evolution of the gliding arc discharge [37,44]. The glow-type discharges are characterized by current peaks of hundreds of milliamperes whereas the spark-type discharges are recognized by current spikes of up to tens of amperes [44]. The glow-type discharges were found to be effective in surface treatment [14] and toluene removal [18].…”