结合光学多通道分析仪和高速摄像仪的观测结果，对6061铝合金CO2激光深熔焊接过程中等离子体的热力学行为进行了研究。分析了稳定的激光焊接过程初始阶段和焊接过程中及焊接过程不稳定时的等离子体热力学行为。实验结果表明，激光深熔焊接在初始阶段，等离子体的电子温度和离子温度偏离较大，并逐渐趋于平衡，温度梯度也逐渐变小；在稳定的焊接过程中激光功率的增加对等离子体的温度影响较小，等离子体尺寸变化对焊缝截面有重要的影响；等离子体温度急剧增加时，小孔内气压的剧增会引起等离子体上下起伏，使焊接过程中断或产生气体，而等离子体尺寸大小的波动则会影响焊缝成形。

The thermodynamics behaviors of laser-induced plasma have been studied during CO2 laser welding on 6061 aluminum alloy with an optical multicultural analyzer and a high-speed camera. The plasma induced by laser in the initial stage and all the welding process have been analyzed in a stable welding process as the same as unstable welding process. The experimental results demonstrate that the deviation between electronic temperature and ionization temperature of plasma is very obvious in the initial stage during laser welding, then tends to balance gradually, in the same time, temperature gradient of plasma become smaller. In the stable welding process, there is only a small influence of laser power increase on temperature of the plasma, but the influence of the plasma′s size on weld area is important. When the plasma temperature increases sharply with the pressure increasing in the keyhole, the plasma will move up and down, it will induce in the interrupt of welding process or produce blowholes. Moreover, the size fluctuation of plasma will worsen weld shaping.