Differences in the acoustic characteristics of DC bias alternating arcs in argon, helium, and nitrogen

Abstract The acoustic effects of gas discharge plasma have received much attention. Previous studies have shown that cold plasma and thermal plasma have different principles of sound generation. In this paper, the differences in the acoustic characteristics of DC bias alternating arc plasma (thermal plasma) in different gas environments (argon, helium, and nitrogen) are investigated by combining experiments and simulations. Many processes in industrial machining involve this arc plasma. It was found that the acoustic characteristics of the arcs of these three gases are significantly different. The two key parameters, electrical and thermal conductivity of the gas, determine the acoustic characteristics of the arc by influencing the electric power of the arc and the heat dissipation through the anode. At the same drive current, the nitrogen arc has the largest voltage drop and the helium arc has the highest electroacoustic conversion efficiency. This results in the acoustic pressure amplitude being helium, nitrogen, and argon in descending order. The research contributes to a deeper understanding of the vocalization mechanism of arc plasma and provides theoretical guidance on gas selection for arc acoustic wave applications.