Multifunctional Laser System for 1D and 2D Imaging Diagnostic for High-Enthalpy Test Facilities

Speckodyne Corp. in collaboration with Plasma TEC, Inc. and Princeton University proposes to develop a novel, multifunctional optical diagnostic platform for kilohertz rate, non-intrusive, quantitative 1D and 2D imaging of relevant gas parameters in arc driven and other high enthalpy ground testing facilities. The platform implements and integrates state-of-the art optical diagnostic techniques that are enabled by femtosecond-based nonlinear optics: hybrid picosecond/femtosecond Coherent Anti-Stokes Raman Scattering (CARS) and Two-photon Absorption Laser induced Fluorescence (TALIF). The hybrid CARS provides single shot point and line measurements of molecular species concentrations and state populations, as well as rotational and vibrational temperatures, whereas the TALIF provides line and planar measurements of atomic oxygen, nitrogen, argon and other atomic species concentrations. Extending the TALIF to the measurement of velocity profiles will also be considered based on atomic fluorescence Femtosecond Laser Electronic Excitation Tagging (FLEET). Both FLEET and hybrid CARS were recently demonstrated in Mach 10 to 18 in nitrogen flow at AEDC Tunnel 9 in Maryland by the Plasma TEC-Speckodyne team. The proposed platform is powered by a single kilohertz-rate femtosecond laser and incorporates a high-speed imaging system. The system architectural strategy is designed to meet transportability requirements and reliable operation in the harsh environment of NASArsquo;s large-scale ground test and evaluation facilities. The completion of the Phase I effort will demonstrate the feasibility of this concept of measuring dissociation fraction, species, nonequilibrium and temperature at kHz rate over the wide range of operational conditions characterizing high-enthalpy wind tunnel flows. The development of the system requirements and specification will support the next-phase effort focused on prototype development, implementation and testing at NASArsquo;s ground-based facilities.