激光深熔焊接时伴随着高电量等离子体的产生。位于小孔上方的等离子体叫做等离子体云 ,而存在于小孔内部的等离子体则称为孔内等离子。本文设计了能直接观测小孔孔内等离子体光发射的实验 ,即用高功率激光焊接夹持铝膜的两片GG17玻璃 ,完全避免了孔外等离子体云对小孔内部孔内等离子体观测的影响。结果表明 ,小孔孔内的孔内等离子体对激光与工件材料的能量耦合有着重要的影响 ,具体表现为焊接深度和焊接宽度的变化 ;当减少两片GG17玻璃所夹持铝膜的厚度 ,即模拟降低小孔孔内等离子体的浓度时 ,可以得到更深的焊接深度 ,此时小孔孔内等离子体的温度相对较低。这就为定量研究小孔孔内等离子体提供了一种新的方法和手段。

Deep penetration laser welding is associated with violent plasma generation characterized by high charge densities. Plasma resides both outside and inside the keyhole, known as plasma plume and keyhole plasma, respectively. In this article, a specially designed setup was used to take firsthand measurements of the light emission of the keyhole plasma in deep penetration laser welding aluminum films clamped in between two pieces of GG17 glass, triumphantly eliminating the impact of the plasma plume covering the keyhole on the observation of keyhole plasma. It was shown that keyhole plasma has considerable effects on the energy transfer efficiency of the incident laser beam to the material, exhibiting various melting width and depth; deeper welding depth as well as lower temperature of the keyhole plasma was obtained when decreasing the densities of the keyhole plasma by reducing the thickness of aluminum films. Furthermore, a technique for quantitative investigation of plasma inside the keyhole in deep penetration laser welding was developed.