Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011, USA.
Opt Lett. 2010 Jul 15;35(14):2430-2. doi: 10.1364/OL.35.002430.
We demonstrate hybrid femtosecond/picosecond (fs/ps) coherent anti-Stokes Raman scattering for high-speed thermometry in unsteady high-temperature flames, including successful comparisons with a time- and frequency-resolved theoretical model. After excitation of the N(2) vibrational manifold with 100 fs broadband pump and Stokes beams, the Raman coherence is probed using a frequency-narrowed 2.5 ps probe beam that is time delayed to suppress the nonresonant background by 2 orders of magnitude. Experimental spectra were obtained at 500 Hz in steady and pulsed H(2)-air flames and exhibit a temperature precision of 2.2% and an accuracy of 3.3% up to 2400 K. Strategies for real-time gas-phase thermometry in high-temperature flames are also discussed, along with implications for kilohertz-rate measurements in practical combustion systems.
我们展示了飞秒/皮秒（fs/ps）混合相干反斯托克斯拉曼散射在非稳态高温火焰中的高速测温技术，包括与时间和频率分辨理论模型的成功比较。在用 100fs 宽带泵浦和斯托克斯光束激发 N2 振动能级后，使用频率窄化的 2.5ps 探测光束探测拉曼相干性，该探测光束通过 2 个数量级的时间延迟来抑制非共振背景。在稳态和脉冲 H2-空气火焰中以 500Hz 的速率获得实验光谱，在 2400K 以下的温度精度为 2.2%，准确度为 3.3%。还讨论了在高温火焰中进行实时气相测温的策略，以及在实际燃烧系统中进行千赫兹速率测量的意义。
