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

doi:10.1299/kikaib.69.623

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 journal › Article › peer-review

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 language	English
Pages (from-to)	623-629
Number of pages	7
Journal	Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
Volume	69
Issue number	679
DOIs	https://doi.org/10.1299/kikaib.69.623
Publication status	Published - Mar 2003
Externally published	Yes

All Science Journal Classification (ASJC) codes

Condensed Matter Physics
Mechanical Engineering

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A study on an analysis of non-equilibrium of rotational temperatures in supersonic free molecular flows by REMPI. / Mori, Hideo; Niimi, Tomohide; Niwa, Kenji; Akiyama, Isao.

In: Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, Vol. 69, No. 679, 03.2003, p. 623-629.

Research output: Contribution to journal › Article › peer-review

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PY - 2003/3

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

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