Z. Szymanski et al., THE SPECTROSCOPY OF THE PLASMA PLUME INDUCED DURING LASER-WELDING OF STAINLESS-STEEL AND TITANIUM, Journal of physics. D, Applied physics, 30(22), 1997, pp. 3153-3162
Results of spectroscopic measurements of laser-induced plasmas under w
elding conditions are presented and discussed. The metals welded were
stainless steel and titanium. It is shown that the intensities of the
atomic lines of metals give information on the peripheral region of th
e plasma plume. The plasma plume parameters are found to be similar fo
r these two metals. The ratios of intensities of the ionic and atomic
lines of the metals give maximum temperatures of about 11000 K. These
temperatures are several thousand kelvins higher than the temperatures
determined from the atomic lines. The plasma plumes over the keyhole
consist of metal vapours diluted by argon used as the shielding gas. T
he electron densities determined from the Stark broadening of the argo
n lines are about 1 x 10(17) cm(-3). The average partial pressure of t
he metal vapours is found to be 0.2 atm, the argon partial pressure 0.
6 atm and the remaining pressure is due to electrons. Equilibrium cond
itions have been examined and it has been found that the plasma is in
local thermal equilibrium.