Fast Diagnostics of Ignition Processes by Excimer Laser Induced Fluorscence of Formaldehyde

Laser induced fluorescence (LIF) has been widely used for nonintrusive diagnostics of combustion processes in engines, furnaces and turbines [1]. The best way to reduce pollutant production in such devices is to avoid high temperature peaks during combustion and to develop lean premixed combustion devices without spontaneous ignition. The LIF of intermediates as formaldehyde can be used to study ignition processes. Especially the hot spot formation leading to knocking combustion was analyzed [2]. This measurements were performed using dye laser systems, but the handling of these systems in technical environments is difficult. In contrast powerful UV excimer lasers are mostly applied in the diagnostics of technical systems. Two dimensional concentration fields of various combustion species as OH, O2 or NO could be registered [1].