纳秒脉冲空气放电的声学特性实验研究

Experimental Study on the Acoustic Characteristics of Nanosecond Pulsed Discharge in Atmospheric Air

纳秒脉冲空气放电发声具有频域响应宽、发声元器件小、适用于某些恶劣的周围环境等诸多优势。在纳秒脉冲空气放电领域,现阶段少有针对其发声过程中电信号与声信号关系以及发声原理开展的研究。为此通过搭建电声联合诊断试验平台,在不同脉冲放电能量、放电气隙距离下对电信号与声信号进行实时采集,总结声压波形随不同试验参数的变化规律。结果显示,单次纳秒脉冲空气放电可以产生脉宽为微秒级的脉冲声波,脉冲声压的幅值随脉冲放电能量和气隙距离的增加而增加,其变化规律为:脉冲放电能量每增加1 mJ,声压峰值提升约3 Pa;气隙距离每增加1 mm,声压幅值提升约20 Pa。基于试验结果,引入气体放电产生声音过程中气体压力的波动方程,提出一种纳秒脉冲放电中由电转换到声的机理假想。

Nanosecond pulse discharge has many advantages in sound production. For example, it owns wider frequency domain response and smaller components, and is suitable for some harsh surrounding environments, etc. In the field of nanosecond pulse air discharge, the researches on the relationship between electrical signal and acoustic signal and the principle of sound generation are rarely available in the literature. In this paper, an experimental platform for electrical and acoustic joint diagnosis was built. The electrical and acoustic signals were collected in real time under different pulse discharge energy and discharge gap distances, and the variation law of the peak sound pressure with different experimental parameters was summarized. The experimental results show that a single nanosecond pulse air discharge can produce pulse sound wave with microsecond pulse width. The amplitude of pulse sound pressure increases with the increase of pulse discharge energy and gap distance. The peak value of sound pressure increases by about 3 Pa for every 1 m J of pulse discharge energy, and about 20 Pa for every 1 mm gap distance. Based on the experimental results, the wave equation of gas pressure in the process of sound generation is introduced, and a mechanism assumption of conversion from electricity to sound in nanosecond pulse discharge is proposed.