Numerical simulations of gas flows through an open, non-contact cell for LA-ICP-MS

Numerical simulations of gas flows through an open, non-contact cell for laser ablation are presented. The cell consists of dual, annular, concentric micro-jet gas arrays to entrain ablated material (the carrier flow) and exclude atmosphere (the curtain flow). This study shows that the design of the cell affords a very high degree of exclusion of atmospheric gases, using a relatively low curtain flow of 2.5 l min-1 (with a carrier flow of 1.2 l min-1 He), and demonstrates the efficacy of the micro-jet arrays in providing an axially symmetric exclusion zone. Minimum particle transit times through the cell were calculated to be of the order of 50-100 ms.