Fig. 1. Typical arc shapes in LADSW (I=60  A) under different laser power configurations: (a) Pure TIG arc, (b) arc column compression, (c) arc root constriction, and (d) arc column expansion shapes occur under P=0, 1.6, 2.0, and 2.8 kW, respectively.

Fig. 2. Schematic diagram of the welding experiment and arc spectral collecting system.

Fig. 3. Arc spectral characteristics of (a) conventional TIG arc, and (b) LADSW (I=60  A, v=1  m/min, and P=2.0  kW).

Fig. 4. Intensities of (a) Al I 396.152 and (b) Ar I 763.511 of the arc plasma on the arc axes with typical arc images.

Fig. 5. Effect of laser power (I=60  A and v=1  m/min) on the spectral intensities of (a) Al I 396.152 and (b) Ar I 763.511.

Fig. 6. Effect of laser power (I=60  A and v=1  m/min) on (a) electron temperature and (b) electron density during LADSW.