Laser-Induced Breakdown Spectroscopy of Hydrocarbon Flame and Rocket Engine Simulator Plume.

Laser-induced breakdown spectroscopy (LIBS) of metal-seeded aerosols and a hydrocarbon flame were studied to determine the proper experimental condition for rocket motor application. LIBS and atomic emission spectroscopy (AES) were also performed in the rocket motor simulator to evaluate both technologies for the health monitoring of the rocket engine. The LIBS signal of the seeded element goes down drastically in the presence of the flame in comparison to the signal obtained from the aerosols of the elements. Similarly the LIBS signal of the trace elements was very weak in the luminous flame and the simulator plume in comparison to the measurement outside it. The intensity of the LIBS signal from the trace elements present in the plume/flame was found to be dependent on the process of seeding, the transition probability, and the decay time of the background emission. Ultimately LIBS was found to be more sensitive than AES in detecting the trace elements in the simulator plume. This study establishes LIBS as an improved health-monitoring system over AES for the plume studied. [ABSTRACT FROM AUTHOR]