Laser Raman Measurements in Supersonic Air Flows Using an EMCCD Detector
Abstract
The study of high-speed reacting flows and their thermochemical properties is an important aspect of modern aerospace engineering. The present work revisited an existing laser Raman spectroscopy system in order to modify the collection-side optics. Specifically, the work implements a new Electron Multiplying Charge Coupled Device (EMCCD) detector and optical system to increase the Signal-to-Noise ratio of the current Raman spectroscopy system. This study aimed to determine if the specific EMCCD with its quick vertical shift transfer would assist in reducing the ambient noise embedded in the data during acquisition and if it could be implemented into the current spectrometer. One of the requirements for utilizing the EMCCD was the incorporation of new lenses that allowed for sufficient spectral bandwidth in the transmissive grating spectrometer. This work concentrated on a novel technique combining vibrational and rotational Raman scattering to directly measure the density and temperature of supersonic, non-isobaric air flows. Pressure was then determined from these two measurements by using the ideal gas law. The Signal-to-Noise ratio of the new EMCCD detector /spectrometer combination was compared. favorably, to the equivalent metric of the old collection system. Future work will utilize the low-noise, fast detector in high-speed reacting flows.
Citation
Fulcher, Benjamin Clark (2023). Laser Raman Measurements in Supersonic Air Flows Using an EMCCD Detector. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /198889.