Experimental study of rotational nonequilibrium in low density N 2 jets using REMPI

Tomohide Niimi, Hideo Mori, Isao Akiyama, Takumi Tsuzuki

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In the present study, we measure the rotational population in supersonic nitrogen free jets using a REMPI (resonantly enhanced multi-photon ionization) method, which is not influenced by secondary electrons, unlike an electron beam method. Nitrogen ions are detected as a REMPI signal and its spectra depending on the wavelength of an irradiated laser beam are analyzed to measure rotational temperature through the Boltzmann plot. Nitrogen gas expands into a vacuum chamber from a sonic nozzle with a D=0.50mm diameter, setting P0D (P0: source pressure), depending inversely on the nozzle Knudsen number, at 15 Torr-mm or lower. In the case of P0D=15.0, the rotational temperature distribution along the centerline of the jet, measured by Boltzmann plot, coincides with Marrone's data measured by electron beam fluorescence, and the rotational relaxation rate Zr calculated by the relaxation equation results in 1.3. However, the non-Boltzmann rotational distribution appears evidently in the supersonic free molecular nitrogen flows for P 0D≤15 Torr-mm and as a decrease in the P0D, the deviation from the Boltzmann distribution and the partial freezing of the population arise more upstream.

Original languageEnglish
Title of host publicationRAREFIED GAS DYNAMICS
Subtitle of host publication24th International Symposium on Rarefied Gas Dynamics, RGD24
Number of pages6
Publication statusPublished - May 16 2005
Externally publishedYes
Event24th International Symposium on Rarefied Gas Dynamics, RGD24 - Bari, Italy
Duration: Jul 10 2004Jul 16 2004

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Other24th International Symposium on Rarefied Gas Dynamics, RGD24

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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