Melt ejection from copper target in air in the presence of magnetic field using nanosecond pulsed laser ablation

The authors report on the study of the crater generated using a nanosecond laser on a copper target in air in the presence of uniform and nonuniform magnetic fields. The analysis of particles deposited inside and around the crater revealed that the generation of large particles (>= 0.68 mu m) is due to the melt ejection and instability in the liquid layer. The presence of a nonuniform magnetic field causes an additional drift to molten liquid which in turn increases the Kelvin-Helmholtz instability. The percentage of large particles increased due to the enhancement in the Kelvin-Helmholtz instability and mass ejection. The intensity of copper atomic transitions was enhanced in the presence of a uniform magnetic field compared to a nonuniform magnetic field. This is more likely due to an increase in melt ejected mass in the plasma in the presence of a nonuniform magnetic field which may scatter or absorb laser light which in turn decreases laser-matter interaction. The energy-dispersive x-ray spectroscopy and Raman spectroscopy showed the deposited particles are Cu2O. In the presence of a nonuniform magnetic field, the intensity of Raman Cu2O was enhanced, which is attributed to an increase in the number of Cu2O particles. (C) 2017 American Vacuum Society.