Monitoring temperature in high enthalpy arc-heated plasma flows using tunable diode laser absorption spectroscopy

Nations, Marcel; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George A.

doi:10.2514/6.2013-2761

Cited by 8 publications

(3 citation statements)

References 9 publications

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“…29 Finally, the lower-state population (number density) was directly determined by integrating the equivalent single-pass absorbance over the spectral feature (eq 3); note that the Voigt lineshape is defined to have an area of unity. 38 The reflectivity values of the CEAS mirrors used here were 99.05% at 777.2 nm and 99.30% at 844.6 nm, which correspond to absorption gain factors of 104 and 142, respectively.…”

Section: Experimental Methodsmentioning

confidence: 84%

“…Here, the measured CEAS absorbance was converted to an equivalent single-pass absorbance (α SP ) where S lu is the linestrength of the atomic transition, n l is the number density in the lower state of the transition, L is the cavity length (same as the shock tube inner diameter), ϕ(ν) is the lineshape function (modeled by the Voigt profile), and G is the absorption gain factor that can be expressed as G = R /(1 – R ), where R is the measured mirror reflectivity . Finally, the lower-state population (number density) was directly determined by integrating the equivalent single-pass absorbance over the spectral feature (eq ); note that the Voigt lineshape is defined to have an area of unity . The reflectivity values of the CEAS mirrors used here were 99.05% at 777.2 nm and 99.30% at 844.6 nm, which correspond to absorption gain factors of 104 and 142, respectively.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

et al. 2016

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The formation of electronically excited atomic oxygen was studied behind reflected shock waves using cavity-enhanced absorption spectroscopy. Mixtures of 1% O-Ar were shock-heated to 5400-7500 K, and two distributed-feedback diode lasers near 777.2 and 844.6 nm were used to measure time-resolved populations of atomic oxygen's S° andS° electronic states, respectively. Measurements were compared with simulated population time histories obtained using two different kinetic models that accounted for thermal nonequilibrium effects: (1) a multitemperature model and (2) a reduced collisional-radiative model. The former assumed a Boltzmann distribution of electronic energy, whereas the latter allowed for non-Boltzmann populations by treating the probed electronic states as pseudospecies and accounting for dominant electronic excitation/de-excitation processes. The effects of heavy-particle collisions were investigated and found to play a major role in the kinetics of O atom electronic excitation at the conditions studied. For the first time, rate constants (k) for O atom electronic excitation from the ground state (P) due to collisions with argon atoms were directly inferred using the reduced collisional-radiative model, k(P → S°) = 7.8 × 10T exp(-1.061 × 10K/T) ± 25% cm s and k(P → S°) = 2.5 × 10T exp(-1.105 × 10K/T) ± 25% cm s.

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Section: Experimental Methodsmentioning

confidence: 84%

Section: Experimental Methodsmentioning

confidence: 99%

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

et al. 2016

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“…Other minor species such as nitrogen dioxide (NO 2 ) and atomic nitrogen (N) also have strong temperature sensitivity, but are present at much lower concentrations. In higher temperature applications, such as arc heaters (T > 4000 K), laser absorption sensing of nitrogen and oxygen atoms has been utilized to measure gas temperature [3,4]. Here we select nitric oxide as the target species for thermometry due to its relative abundance from 1500-3000 K and convenient spectroscopic activity in the infrared.…”

Section: Chemical Equilibriummentioning

confidence: 99%

Laser absorption of nitric oxide for thermometry in high-enthalpy air

Spearrin

Schultz

Jeffries

et al. 2014

Meas. Sci. Technol.

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The design and demonstration of a laser absorption sensor for thermometry in high-enthalpy air is presented. The sensor exploits the highly temperature-sensitive and largely pressure-independent concentration of nitric oxide in air at chemical equilibrium. Temperature is thus inferred from an in situ measurement of nascent nitric oxide. The strategy is developed by utilizing a quantum cascade laser source for access to the strong fundamental absorption band in the mid-infrared spectrum of nitric oxide. Room temperature measurements in a high-pressure static cell validate the suitability of the Voigt lineshape model to the nitric oxide spectra at high gas densities. Shock-tube experiments enable calibration of a collision-broadening model for temperatures between 1200–3000 K. Finally, sensor performance is demonstrated in a high-pressure shock tube by measuring temperature behind reflected shock waves for both fixed-chemistry experiments where nitric oxide is seeded, and for experiments involving nitric oxide formation in shock-heated mixtures of N2 and O2. Results show excellent performance of the sensor across a wide range of operating conditions from 1100–2950 K and at pressures up to 140 atm.

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A laser diagnostic for lineshape-based gas temperature and pressure measurements targeting a single atomic potassium absorption transition

Vandervort,

Schwartz,

Barnes

et al. 2024

Appl. Phys. B

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Monitoring temperature in high enthalpy arc-heated plasma flows using tunable diode laser absorption spectroscopy

Cited by 8 publications

References 9 publications

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

Laser absorption of nitric oxide for thermometry in high-enthalpy air

A laser diagnostic for lineshape-based gas temperature and pressure measurements targeting a single atomic potassium absorption transition

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Monitoring temperature in high enthalpy arc-heated plasma flows using tunable diode laser absorption spectroscopy

Cited by 8 publications

References 9 publications

Kinetics of Excited Oxygen Formation in Shock-Heated O2–Ar Mixtures

Kinetics of Excited Oxygen Formation in Shock-Heated O2–Ar Mixtures

Laser absorption of nitric oxide for thermometry in high-enthalpy air

A laser diagnostic for lineshape-based gas temperature and pressure measurements targeting a single atomic potassium absorption transition

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Product

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Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures

Kinetics of Excited Oxygen Formation in Shock-Heated O₂–Ar Mixtures