Shock Tube Study of Weakly Ionized Plasmas Using Laser Absorption Spectroscopy of Excited State Oxygen Atoms PDF Download

Author: Yang Li
Publisher:
ISBN:
Category :
Languages : en
Pages :

Get Book Here

Book Description
This work studies the collisional excitation kinetics of atomic oxygen diluted in argon at extreme temperatures (8,000 - 11,000 K) in a shock tube. Two lasers at 777 and 926 nm were scanned across the transitions of atomic oxygen at a rate of 25 kHz, providing the absorbance time histories within the 0.5-1 ms test time after the reflected shock passed. Four key quantities were measured in the current work to understand the collisional excitation kinetics, namely, the number density of the: fourth level of atomic oxygen; sixth level of atomic oxygen; electrons; and heavy-particle translational temperature. The number density of atomic oxygen and heavy-particle translational temperature were inferred from the integrated area and the Doppler linewidth of the measured oxygen absorbance. A preliminary two-temperature collisional-radiative model was developed to explain the multi-stage behavior of the measured oxygen number density time histories from 8,000 to 10,000 K. Reaction rate constants were fitted to match the measured excited-state atomic oxygen time histories. A sensitive, in-situ electron number density diagnostic method was developed by measuring the Stark shift of excited-state atomic oxygen. The measured electron number density was consistent with the preliminary model. The kinetics model was revised to match the measured time histories from 10,000 to 11,000 K.