The Application of Planar Laser-Induced Fluorescence as a Diagnostic in Plasma Processing

ABSTRACTThis paper reports an application of the planar laser-induced fluorescence (PLIF) technique to visualize species in a plasma jet. For the experiment, 10 μm manganese particles were injected through a center feed in the cathode of a 8 kW plasma torch. A tunable laser beam (−20 mJ/pulse) was focused by a cylinderical lens into a sheet, approximately 2.4 cm high and 550 μm thick, which passed through the center of the plasma plume, exciting manganese lying within the plane defined by the laser. The fluorescence generated was imaged onto a gated, intensified CID camera, converted to digital format, and processed by an image analyzer to form a 2-D map of the relative manganese vapor concentration within the plasma. The results of this proof-of-principle experiment demonstrate that the PLIF measurement holds considerable promise for obtaining simultaneous spatially resolved measurements of species concentration.