High-speed 2D Raman imaging at elevated pressures

Two-dimensional (2D) Raman scattering at 10 kHz in non-reacting flow mixtures is demonstrated by employing a burst-mode laser with a long-duration pulse of about 70 ns and pulse energy of about 750 mJ at 532 nm. To avoid optical breakdown, the pulse width of the laser was varied in the range of 10-1000 ns. The effects of pulse shape, pulse energy, and harmonic conversion on 2D measurements are also studied. The applications of high-speed, single-shot, 2D imaging of CH₄ and H₂ jets in N₂ at elevated pressures are demonstrated. In addition, the scalar dissipation rate of CH₄ in N₂ at 20 bar is determined, and multi-dimensional, multi-species, high-speed imaging of flows at elevated pressures is demonstrated.