Detailed studies of the plume deflection effect during long laser irradiation of solid targets

The changes of the laser ablated target morphology and the corresponding plume deflection angle have been studied. As the number of laser pulses/site increases, the target morphology changes and produces a visible deviation of the plasma plume. Scanning electron microscopy analyses of the target surface allowed us to correlate the plume deflection angle to the target roughness and, hence, to the number of laser pulses/site. The deflection effect has been observed for all the targets used (Ti, Si, Cu, Al–Sn alloy, graphite and magnetic compounds) and for whatever target surface morphology produced by laser irradiation. As earlier models explaining the origin of the plume deflection are not universal and less than ever satisfactory, we suggest a simple model that seems to be more realistic and general.