脉冲激光打孔声波产生机理研究

摘要

In order to study the mechanism of acoustic signal emission during laser drilling,acoustic and shock wave signal during laser drilling process were detected by microphone and PVDF sensor,the difference of acoustic signal was compared and analyzed when O2 was assisted gas and there was no assisted gas.Study results showed that the la-ser induced plasma shock wave when laser interact with materials is the main reason that generates the sound wave during percussion laser drilling process.Assist gas isn’t the necessary condition that generates sound wave.When assisted gas is O2 ,it can reduce the shielding effect of plasma and vapor on laser and maintain a continual output of sound wave;the oxidizing reaction between O2 and materials can enhance the shielding effect of plasma and vapor tem-porarily and lead to the discontinuous of the sound wave’s output.%为了研究激光打孔过程中声波信号产生机理。利用电容传声器、PVDF传感器分别测量了激光打孔过程中的声波型号与冲击波信号，比较并分析了氧气为辅助气体、无辅助气体时声波信号的异同。研究结果表明：激光作用于孔内材料诱导产生的等离子体冲击波是激光打孔过程中产生声波的主要原因；辅助气体不是产生声波信号的必要条件；氧气作为辅助气时起到两方面作用：一方面，气流的物理作用减弱材料蒸汽和等离子对激光的屏蔽效应，维持较为连续的声波信号输出；另一方面，氧气的化学作用会增强材料蒸汽和等离子的屏蔽效应。氧气的物理作用与化学作用交替进行产生了不连续的声波信号。