Quality improvement of laser beam welds by plasma control

Improvement of laser keyhole formation with the assistance of arc plasma in the hybrid welding process of magnesium alloy

“…During the process of high-power laser welding, when the keyhole forms, the dense plasma induced by laser beam will absorb the laser energy by the inverse Bremsstrahlung process and defocus the laser beam [11], which decrease the energy absorbed by the target metal. So many techniques have been developed to control the electron density in high-power laser welding, especially for CO 2 laser [12][13][14]. In the present experiment, the laser-induced plasma sprays away from the target metal with a gradient from the incident direction of laser beam due to effect of arc plasma and Ar shielding gas, so the negative effect induced by the dense plasma to absorb and defocus laser beam is weakened.…”

Laser Welding: Techniques of Real Time Sensing and Control Development

“…In a special plasma charge sensor (PCS) based on plasma density and ionization variation is implemented to measure weld penetration and detect weld defects. Some other researches are also involved with direct mode estimation (Morgan 1990, Sun 1993) to assist better control development.…”

Effect of applying electrical potential to a CO2 laser welding of different thickness plates

“…A laser welding with an argon gas shielding is that generated plasma on the plate heats itself [5,6]. The injected argon gas is ionized by the energy of the laser beam passing through the plate.…”