Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy
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| Language: | English |
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The Ohio State University / OhioLINK
2012
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=osu1345522814 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu1345522814 |
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oai_dc |
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NDLTD |
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English |
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| topic |
Engineering Experiments Mechanical Engineering Optics Plasma Physics CARS spectroscopy nonequilibrium plasma diagnostics Nitrogen vibrational distribution function |
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Engineering Experiments Mechanical Engineering Optics Plasma Physics CARS spectroscopy nonequilibrium plasma diagnostics Nitrogen vibrational distribution function Montello, Aaron David Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy |
| author |
Montello, Aaron David |
| author_facet |
Montello, Aaron David |
| author_sort |
Montello, Aaron David |
| title |
Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy |
| title_short |
Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy |
| title_full |
Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy |
| title_fullStr |
Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy |
| title_full_unstemmed |
Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy |
| title_sort |
studies of nitrogen vibrational distribution function and rotational-translational temperature in nonequilibrium plasmas by picosecond coherent anti-stokes raman scattering spectroscopy |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2012 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1345522814 |
| work_keys_str_mv |
AT montelloaarondavid studiesofnitrogenvibrationaldistributionfunctionandrotationaltranslationaltemperatureinnonequilibriumplasmasbypicosecondcoherentantistokesramanscatteringspectroscopy |
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1719431005018783744 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu13455228142021-08-03T06:06:31Z Studies of Nitrogen Vibrational Distribution Function and Rotational-Translational Temperature in Nonequilibrium Plasmas by Picosecond Coherent Anti-Stokes Raman Scattering Spectroscopy Montello, Aaron David Engineering Experiments Mechanical Engineering Optics Plasma Physics CARS spectroscopy nonequilibrium plasma diagnostics Nitrogen vibrational distribution function <p>Picosecond Coherent Anti-Stokes Raman Scattering (CARS) is used for measurements of nitrogen Q-branch (ΔJ=0) spectra in several non-equilibrium plasma environments; spectral processing yields vibrational distribution function (VDF), 1st-level vibrational temperature (Tv), and/or rotational-translational temperature (Trot). The implementation of a home built modeless dye laser and portable CARS system is also described.</p><p>Simultaneous measurements of Tv and Trot were performed in the 200–370torr plenum of a nonequilibrium Mach 5 wind tunnel. The nominally high reduced electric field (E/npeak~500Td), nsec-pulsed discharge alone results in fairly significant vibrational loading, Tv~720K/Trot~380K; addition of an orthogonal low E/n (~10Td) DC sustainer discharge produces substantial vibrational non-equilibrium, Tv~2000K/Trot~450K. Injection of CO2, NO, and H2 downstream of the pulser-sustainer discharge is examined, resulting in vibrational relaxation and simultaneous gas heating, Tv~800-1000K/Trot~600K.</p><p>CARS measurements within very low density flows in the Mach 5 expansion nozzle are also performed, with Tv measured in both the supersonic free-stream and downstream of a bow shock created by a 5mm diameter cylindrical test object in the Mach 5 flow. Measurements within 300μm of the cylinder surface show that for pure N2, or N2 with 0.25torr CO2 injection, no vibrational relaxation is observed behind the bow shock.</p><p>A third set of data is reported from measurements of Tv and Trot produced in a plasma assisted combustion reactor. Non-equilibrium vibrational loading is examined for bursts of 40-150 pulses in 100torr air at T0=300K; vibrational energy is seen to increase quasi-linearly with number of pulses, up to ~100 pulses, after which vibrational temperature levels off Tv~1300K. These results are found to agree well with nsec discharge modeling predictions. Vibrational energy decay is examined in 100 and 300torr air, for T0=300 and 500K for a variety of discharge burst sizes, and it is noted that the T0=500K condition exhibits vibrational energy decay nearly an order of magnitude faster than that observed for T0=300K. Additionally, Trot was measured for bursts of 50 pulses, at T0=500K, in air as well as C2H4-, CH4-, and H2-air mixtures, for P0=100, 200, 300torr, φ~0.9-0.36. This analysis shows no significant dependence of Trot on any of the parameters, except for differences between fuel species. Time-resolved thermometry of H2-air excitation and ignition is reported, with ignition delay time and peak temperature found in good agreement with kinetic modeling calculations.</p><p>A final data set involved the measurement of VDF and Trot in a single-filament-pulse nsec-duration discharge in 100torr N2/air. Various energy loading conditions are examined, with high vibrational non-equilibrium observed in all cases. Broadening of the dye laser spectral profile allows simultaneous interrogation of N2(X,v=0-9). Immediately after the ~100nsec pulse moderate vibrational non-equilibrium is observed, with Tv~600-1000K, and Trot~300-400K for all conditions. Very notable is the presence of a peak in Tv typically occurring ~100 μsec after the discharge pulse, with Tv(peak)~1400-2600K, depending on the discharge energy loading. Total vibrational quanta was also plotted; this peaks at a similar time as Tv, and also exhibits an increase of 2-4 times the value observed immediately after the pulse.</p> 2012-08-30 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1345522814 http://rave.ohiolink.edu/etdc/view?acc_num=osu1345522814 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |