Femtosecond Coherent Anti-Stokes Raman Scattering for Time-Resolved Measurements of Temperature and Species Concentrations in Flames

飞秒相干反斯托克斯拉曼散射用于火焰中温度和物质浓度的时间分辨测量

• 批准号: 0413623
• 负责人: Robert Lucht
• 金额: --
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0413623&HistoricalAwards=false
• 关键词: Femtosecond; Coherent; Anti; Stokes; Raman

PROJECT ABSTRACT: Femtosecond Coherent Anti-Stokes Raman Scattering for Time-Resolved Measurements of Temperature and Species Concentration in FlamesRobert P. Lucht and Xianfan Xu School of Mechanical Engineering, Purdue University, W. Lafayette, IN 47907-2088The primary objective of the proposed work is the development and application of ultrafast-laser-based coherent anti-Stokes Raman scattering (CARS) techniques for single-shot measurements of temperature and species concentrations at data rates of 1 kHz or greater. The acquisition of fully time-resolved data from turbulent media will provide more rigorous and meaningful tests of turbulent flame models, leading eventually to combustors that are more efficient and have lower levels of pollutant emission. The 1-kHz data rate of the measurements will be a great advantage during testing of practical combustors, especially when the test duration is limited by facility considerations. The work represents a first step toward enabling femtosecond CARS based sensors for energy and environment applications. The proposed research will provide excellent training for graduate students in mechanical engineering. The femtosecond (fsec) CARS project will provide numerous opportunities for multidisciplinary activities for mechanical engineering graduate students, because operation of the fsec laser systems requires considerable expertise in optical physics and electronics. The subjects of fsec laser systems and fsec laser physics will be incorporated in a graduate class on advanced laser diagnostics. Students from underrepresented groups will be actively recruited for this research, at both the undergraduate and graduate levels. To assist in undergraduate and graduate recruitment, a fsec CARS project web site will be created. The femtosecond CARS measurements will be performed using an existing laser facility at Purdue University; laser pulses at 780 nm with a nominal pulse length of 80 fsec can be generated with pulse energies in excess of 1 mJ at a repetition rate of 1 kHz. Pump and probe pulses will be produced using an optical parametric amplifier. To measure temperature and/or species concentrations at data rates of 1 kHz or greater, a chirped-pulse probe beam with a pulse length of 2-3 psec will be used to map the temporal behavior of the Raman coherence onto the frequency spectrum of the CARS signal. The CARS signal will be dispersed using a spectrometer and detected using a back-illuminated electron multiplying CCD (EMCCD). This EMCCD camera has been developed as a frame transfer camera and CARS spectra can be extracted at data rates of 1 kHz or greater. Unique numerical methods for calculation of the fsec CARS signal generation process will be used to both explore the physics of the fsec CARS process, including the details of the interaction of the pump and Stokes beams to create the Raman coherence, and to develop computer codes for determination of temperatures and species concentrations from experimental data.

项目摘要：飞秒相干反斯托克斯拉曼散射用于火焰中温度和物质浓度的时间分辨测量Robert P. Lucht 和 Xianfan Xu 普渡大学机械工程学院，W. Lafayette，IN 47907-2088拟议工作的主要目标是基于超快激光的相干反斯托克斯拉曼散射（CARS）技术的开发和应用以 1 kHz 或更高的数据速率单次测量温度和物质浓度。 从湍流介质中获取完全时间分辨的数据将为湍流火焰模型提供更严格和更有意义的测试，最终导致燃烧室效率更高、污染物排放水平更低。 在实际燃烧器的测试过程中，1kHz 的测量数据速率将具有很大的优势，特别是当测试持续时间受到设施考虑的限制时。 这项工作代表了实现基于飞秒 CARS 的传感器在能源和环境应用中的第一步。 拟议的研究将为机械工程研究生提供良好的培训。 飞秒 (fsec) CARS 项目将为机械工程研究生提供大量多学科活动的机会，因为 fsec 激光系统的操作需要相当多的光学物理和电子学专业知识。 fsec 激光系统和 fsec 激光物理科目将纳入高级激光诊断研究生班。 来自代表性不足群体的学生将被积极招募本科生和研究生参与这项研究。 为了协助本科生和研究生的招聘，将创建一个 fsec CARS 项目网站。 飞秒 CARS 测量将使用普渡大学现有的激光设施进行； 780 nm 的激光脉冲，标称脉冲长度为 80 fsec，脉冲能量超过 1 mJ，重复频率为 1 kHz。 泵浦和探测脉冲将使用光学参量放大器产生。 为了以 1 kHz 或更高的数据速率测量温度和/或物质浓度，将使用脉冲长度为 2-3 皮秒的啁啾脉冲探测光束将拉曼相干性的时间行为映射到拉曼相干性的频谱上。汽车信号。 CARS 信号将使用光谱仪进行分散，并使用背照式电子倍增 CCD (EMCCD) 进行检测。 该 EMCCD 相机已开发为帧传输相机，可以以 1 kHz 或更高的数据速率提取 CARS 光谱。 用于计算 fsec CARS 信号生成过程的独特数值方法将用于探索 fsec CARS 过程的物理原理，包括泵浦和斯托克斯光束相互作用的细节以创建拉曼相干性，并开发计算机代码根据实验数据确定温度和物种浓度。