A study on an analysis of non-equilibrium of rotational temperatures in supersonic free molecular flows by REMPI

Hideo Mori, Tomohide Niimi, Kenji Niwa, Isao Akiyama

Research output: Contribution to journalArticle

Abstract

In highly rarefied gas flows, there appear nonequilibrium phenomena not only between translational and rotational energy modes (non-equipartition) but also deviation of rotational energy distribution from the Boltzmann distribution. To analyze these highly rarefied gas flows, we established the experimental system for 2R + 2 N2-REMPI and applied it to the measurement of rotational temperature in a supersonic free molecular flow of nitrogen. In this study, a strong nonequilibrium in rotational energy mode has been found in a nitrogen free molecular flow. The data in the Boltzmann plot, obtained from the measured REMPI spectra, cannot be fitted by one line but approximately by two lines, revealing the non-Boltzmann distribution of rotational energy in the ground state. The mechanism of the deviation from the Boltzmann distribution is also discussed using the state-to-state transition rates for collisional relaxation.

Original languageEnglish
Pages (from-to)623-629
Number of pages7
JournalNippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
Volume69
Issue number679
DOIs
Publication statusPublished - Jan 1 2003
Externally publishedYes

Fingerprint

free molecular flow
Flow of gases
Boltzmann distribution
rarefied gases
Nitrogen
gas flow
Ground state
deviation
nitrogen
Temperature
temperature
energy
energy distribution
plots
ground state

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering

Cite this

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abstract = "In highly rarefied gas flows, there appear nonequilibrium phenomena not only between translational and rotational energy modes (non-equipartition) but also deviation of rotational energy distribution from the Boltzmann distribution. To analyze these highly rarefied gas flows, we established the experimental system for 2R + 2 N2-REMPI and applied it to the measurement of rotational temperature in a supersonic free molecular flow of nitrogen. In this study, a strong nonequilibrium in rotational energy mode has been found in a nitrogen free molecular flow. The data in the Boltzmann plot, obtained from the measured REMPI spectra, cannot be fitted by one line but approximately by two lines, revealing the non-Boltzmann distribution of rotational energy in the ground state. The mechanism of the deviation from the Boltzmann distribution is also discussed using the state-to-state transition rates for collisional relaxation.",
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AU - Mori, Hideo

AU - Niimi, Tomohide

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AU - Akiyama, Isao

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AB - In highly rarefied gas flows, there appear nonequilibrium phenomena not only between translational and rotational energy modes (non-equipartition) but also deviation of rotational energy distribution from the Boltzmann distribution. To analyze these highly rarefied gas flows, we established the experimental system for 2R + 2 N2-REMPI and applied it to the measurement of rotational temperature in a supersonic free molecular flow of nitrogen. In this study, a strong nonequilibrium in rotational energy mode has been found in a nitrogen free molecular flow. The data in the Boltzmann plot, obtained from the measured REMPI spectra, cannot be fitted by one line but approximately by two lines, revealing the non-Boltzmann distribution of rotational energy in the ground state. The mechanism of the deviation from the Boltzmann distribution is also discussed using the state-to-state transition rates for collisional relaxation.

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