FLUORESCENCE SPECTROSCOPY AND THERMOMETRY FOR HYPERSONIC FLIGHT RESEARCH

TWO INNOVATIVE INSTRUMENTS FOR FLIGHT RESEARCH, A STEADY-STATE SPECTROFLUORIMETER AND A LASER-INDUCED-FLUORESCENCE THERMOMETER, ARE PROPOSED FOR NONINTRUSIVE MEASUREMENTS AT MACH NUMBERS BETWEEN 4 AND 15 IN THE MIDDLE ATMOSPHERE. THE SPECTROFLUORIMETER WOULD PROVIDE INFORMATION ABOUT AMBIENT AIR CONSTITUENTS AND THEIR FLUORESCENCE CHARACTERISTICS NEAR THE LIMITS OF INTEREST FOR AIRBREATHING PROPULSION AND AERODYNAMIC HEATING. IN ADDITION TO THEIR INTRINSIC VALUE, THESE RESULTS WOULD CONTRIBUTE TO THE OPTIMAL DESIGN OF A TIME-RESOLVED LASER-INDUCED-FLUORESCENCE THERMOMETER WHICH WOULD OBTAIN DISTRIBUTIONS OF MEAN AND FLUCTUATING TEMPERATURE IN THE BOUNDARY LAYER OF FLIGHT RESEARCH VEHICLES, FOR EXAMPLE HYPERSONIC CONES. THE TIME-RESOLVED MEASUREMENT OF FLUORESCENCE CHARACTERISTICS FOR TEMPERATURE IS ALSO INNOVATIVE AND IS REQUIRED TO OBTAIN USEFUL RESULTS AT LOW FLUORESCENCE INTENSITIES AND TO QUANTIFY QUENCHING CORRECTIONS THAT HAVE PREVIOUSLY INTRODUCED UNACCEPTABLE UNCERTAINTIES AND PREVENTED PRACTICAL APPLICATION OF FLUORESCENCE TO FLIGHT RESEARCH. PHASE I WOULD PROVIDE FEASIBILITY ASSESSMENTS OF BOTH INSTRUMENTS, WOULD TEST A PROTOTYPE SPECTROFLUORIMETER AND WOULD PLACE EMPHASIS ON THE TWO MOST CRITICAL ASPECTS WHICH ARE THE ADEQUATE RESOLUTION OF FLUORESCENCE SIGNALS AND THE FLUORESCENCE CHARACTERISTICS OF THE REAL GASES AT THE PROPOSED ALTITUDES AND SPEEDS. FINAL ENGINEERING DESIGN OF THE SPECTROFLUORIMETER, FLIGHT-HARDENING, ASSOCIATED MECHANICAL TESTING, RESEARCH AND DEVELOPMENT OF THE TIME-RESOLVED FLUORESCENCE THERMOMETER, ITS REFINEMENT AND OPTIMIZATION WOULD ALL BE ADDRESSED IN PHASE II. PHASE II WOULD PROVIDE PROVEN PROTOTYPES OF THE SPECTRAL FLUORIMETER AND FLUORESCENCE THERMOMETER WITH THE NECESSARY FEATURES FOR PHASE III INSTALLATION AND FLIGHT MEASUREMENTS.