Spectroscopic investigations of CO and CO2 laser-induced aluminum welding plasmas

Average electron densities and temperatures were measured for both carbon and carbon-dioxide laser induced aluminum welding plasmas using spectroscopic techniques. The plasma temperature is smaller in the case of carbon laser welding, whereas the electron density is slightly higher. Therefore the absorption length (inverse bremsstrahlung) of the carbon laser radiation in the welding zone is a factor of 2 to 7 longer. This is the reason for the better weld seam quality obtained with the carbon laser.