Experimental study on the discharge characteristics of air rotating gliding arc

In this study, the discharge characteristics of air rotating gliding arc are investigated by the synchronous measurements of digital oscilloscope and high-speed camera, and emission spectrum. The discharge evolution in one complete motion cycle exhibits “breakdown-elongation-extinction” process accompanied by the jump of arc root and back-breakdown phenomenon. The discharge evolves from the unstable breakdown mode (U-B), to the transition mode and finally to the stable gliding mode (S-G) by increasing the input voltage or decreasing the tangential and axial gas flow rates. The U-B mode at the input voltage of 120 V is featured by the large reduced electric field and high electron temperature of 1.90 eV, but the arc length and existence time are very short. The S-G mode at the input voltage of 270 V has relatively low breakdown frequency of 0.33 kHz and average breakdown current of 1.31 A, implying that the arc steadily glides and rotates along the spiral electrode. The average electron temperature is 0.64 eV in S-G mode, while the arc length and existence time are longer. The rotational and vibrational temperatures of N2 state are respectively measured to 2200 K and 4400 K in U-B mode, and in S-G mode are 2600 K and 4820 K. From the evolution of emission intensities of measured excited species, it is found that the NOγ band emission intensity generally rises from U-B mode to S-G mode since the gas temperature and arc existence time rise, indicating that S-G mode may be beneficial for the vibrationally-promoted Zeldovich reactions. This study could deepen the understanding of arc characteristics in air rotating gliding arc for selecting a suitable mode to achieve better plasma performance in practical applications.