kHz laser diagnostics using the 'Advanced Disk Laser' - Visualization of turbulent processes via Laser Induced Fluorescence

摘要

We report on a newly developed diode-pumped solid-state-laser system based on the disk laser architecture. The main feature of this Yb:YAG laser is a repetition rate of up to 2 kHz. After amplification and frequency conversion of the fundamental wavelength (around 1030 nm) to the UV spectral range (via third/fourth harmonics generation,) e.g. formaldehyde and OH-radicals can be excited selectively. Both molecules represent very important species in combustion processes. Measuring their time-resolved concentration distributions via their characteristic planar laser induced fluorescence (PLIF) allows investigating propagation of the flame front (OH) or the homogeneity of the fuel distribution (formaldehyde). The combination of a high repetition rate laser system with a fast detection technique -reached by an intensified kHz-camera - enables a ms-time resolution, which is used for visualization of concentration distributions in turbulent processes in real time.