MID-IR LASER ABSORPTION SPECTROSCOPY MEASUREMENTS OF TEMPERATURE AND CARBON MONOXIDE IN A ROTATING DETONATION ROCKET ENGINE

Laser absorption spectroscopy has enabled fast and precise diagnostics for measuring gas conditions in a wide variety of applications. This thesis presents a high-speed mid-IR LAS diagnostic for CO and demonstrates its capabilities by taking measurements inside the annulus of a rotation detonation rocket engine. This scanned direct absorption diagnostic utilizes a quantum cascade laser to interrogate CO absorption lines near 2008.5 cm^-1 to measure temperature, pressure, and CO at 750 kHz. This diagnostic reports precise measurements (95% CI of < 10%) even at elevated temperatures (2500 K) and pressures (6 atm). The presented diagnostic is the first of its kind to permit mid-infrared measurement of CO inside an RDRE annulus at repetition rates > 100 kHz.