Investigation of the spatial and temporal distribution of plasma excited species produced in laser ablation–glow discharge

Abstract

Laser Ablation and Glow Discharge (LAGD) plasmas have been coupled and optical emission measurements have been performed in order to study the spatial and temporal distribution of LA and GD species and hence to get further insights into the interaction between them. The relative delay between the laser event and the emission measurement along the GD pulse has been found as a crucial parameter. In addition, no post excitation of the ablated material has been observed when laser ablation takes place during GD prepeak or plateau. In contrast, emission enhancements (e.g. Al I lines at ~877nm presented an enhancement of up to 4 times in the LAGD plasma) were obtained during the afterglow or late plateau, when firing the laser at delays close (<100μs) to GD pulse termination. Penning ionization of the ablated material within the GD afterglow, followed by recombination processes, seems to account for the emission enhancements obtained when combining laser ablation and glow discharge.