Laser-induced breakdown spectroscopy in a metal-seeded flame

Laser-induced breakdown spectroscopy (LIBS) has been used to detect atomic and molecular species in various environments. It has the capability to be used as a real time monitor in a harsh and turbulent environment. LIBS has been tested at the Diagnostic Instrumentation and Analysis Laboratory's (DIAL) combustion facility to optimize and characterize the LIBS operation in a flame. Three metals, Cu, Fe, and Ca, were injected into the combustor with a peristaltic pump. LIBS spectra were recorded at different delay times with a fixed gate width to determine the best detection gate. LIBS signal in the flame were also compared with the direct emission from the flame. It is found that the LIBS signal is stronger than the signal from the direct emission of the metal in the same flame and the LIBS method has a much better signal over background ratio. To test the calibration scheme, metal solutions were injected into the combustor with different rates. Linear calibration curves were obtained.