Free Stream Test Conditions Determination in ICP Wind Tunnels Using the TALIF Measurement Technique

Playez, M.; Fletcher, Douglas G.

doi:10.2514/6.2008-4254

Cited by 4 publications

(1 citation statement)

References 6 publications

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“…Observation of single-lasershot non-resonant CARS spectra acquired in argon over a sampling window of several minutes revealed no systematic variation in center frequency or bandwidth, which would be the most likely error-based cause of long-time drift in our CARS temperatures. Previous characterization of this plasma torch facility showed 180 Hz fluctuations in plume luminosity [13], which result from imperfect rectification of the 60 Hz AC line frequency, as previously reported for other inductively coupled plasma flow facilities [36,37]. Downsampling of plume luminosity data to the 10 Hz Nd:YAG laser repetition rate revealed aliased low-frequency content near 0.05 Hz, consistent with the observed ∼ 20 s period, in particular at 𝑟 = 11 mm in Fig.…”

Section: Temperature Time-seriessupporting

confidence: 87%

Nitrogen thermometry in an inductively coupled plasma torch using broadband nanosecond coherent anti-Stokes Raman scattering

Fries,

Stark,

Murray

et al. 2023

Appl. Opt.

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The development of atmospheric hypersonic flight and re-entry capabilities requires the characterization of the thermo-chemical state of representative test environments. This study demonstrates the usage of multiplex nanosecond N2 coherent anti-Stokes Raman scattering (CARS) to measure temperatures in an atmospheric, high-temperature (>6000K), air plasma plume, generated by an inductively coupled plasma torch. These are some of the highest temperatures ever accessed via gas-phase CARS, to our knowledge. Temperatures of N2 in the equilibrium plasma plume are determined via theoretical fits to measured CARS spectra. We discuss the practical implementation of CARS at very high temperatures, including the scaling of the N2 CARS signal strength from 300 to 6700 K, where the expected peak signal from the high-temperature plasma torch gases is two orders of magnitude less than commonly encountered in combustion environments. An intensified CCD camera enables single-laser-shot detection at temperatures as high as 6200 K, by increasing sensitivity and providing a time gate against intense background luminosity. We also discuss the impacts of unwanted two-beam CARS contributions from outside the nominal three-beam measurement volume. We present mean axial and radial temperature profiles, as well as time-series data derived from both single-laser-shot and accumulated CARS spectra. The single-laser-shot precision is 1.7%–2.6% at temperatures of 3500 to 6200 K. The presented results pave the way for the use of CARS at very high temperatures and the measurement of spatially resolved interface processes in high-enthalpy flows.

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Section: Temperature Time-seriessupporting

confidence: 87%

Nitrogen thermometry in an inductively coupled plasma torch using broadband nanosecond coherent anti-Stokes Raman scattering

Fries,

Stark,

Murray

et al. 2023

Appl. Opt.

View full text Add to dashboard Cite

show abstract

Nitrogen Thermometry in an Inductively Coupled Plasma Torch using Broadband Nanosecond Coherent Anti-Stokes Raman Scattering

Fries¹,

Murray²,

Stark³

et al. 2023

Preprint

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The development of atmospheric hypersonic flight and re-entry capabilities requires the characterization of the thermo-chemical state of representative test environments. This study demonstrates the usage of multiplex nanosecond N₂ Coherent Anti-Stokes Raman Scattering (CARS) to measure temperatures in an atmospheric, high-temperature (>6000 K), air plasma plume, generated by an inductively coupled plasma torch. These are some of the highest temperatures ever accessed via gas-phase CARS. Temperatures of N₂ in the equilibrium plasma plume are determined via theoretical fits to measured CARS spectra. We discuss the practical implementation of CARS at very high temperatures, including the scaling of the N₂ CARS signal strength from 300 to 6700 K, where the expected peak signal from the high temperature plasma torch gases is two order-of-magnitude less than commonly encountered in combustion environments. An intensified CCD camera enables single-laser-shot detection at temperatures as high as 6200 K, by increasing sensitivity and providing a time gate against intense background luminosity. We also discuss the impacts of unwanted two-beam CARS contributions from outside the nominal three-beam measurement volume and population transfer due to stimulated Raman pumping. We present mean axial and radial temperature profiles, as well as time-series data derived from both single-laser-shot and accumulated CARS spectra. The single-laser-shot precision is 1.7-2.6% at temperatures 3500 to 6200 K. The presented results pave the way for the use of CARS at very high temperatures and the measurement of spatially resolved interface processes in high-enthalpy flows.

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Flow Property Measurements Using Laser-Induced Fluorescence in the NASA Ames Interaction Heating Facility Arc Jet

Grinstead

Porter²,

Carballo

2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Free Stream Test Conditions Determination in ICP Wind Tunnels Using the TALIF Measurement Technique

Cited by 4 publications

References 6 publications

Nitrogen thermometry in an inductively coupled plasma torch using broadband nanosecond coherent anti-Stokes Raman scattering

Nitrogen thermometry in an inductively coupled plasma torch using broadband nanosecond coherent anti-Stokes Raman scattering

Nitrogen Thermometry in an Inductively Coupled Plasma Torch using Broadband Nanosecond Coherent Anti-Stokes Raman Scattering

Flow Property Measurements Using Laser-Induced Fluorescence in the NASA Ames Interaction Heating Facility Arc Jet

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