High-pressure and high-temperature gas cell for absorption spectroscopy studies at wavelengths up to 8 µm. (April 2019)

• Record Type: Journal Article
• Authors: Schwarm, Kevin K.; Dinh, Huy Q.; Goldenstein, Christopher S.; Pineda, Daniel I.; Spearrin, R. Mitchell
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 227(2019)
• Page Start: 145
• Page End: 151
• Publication Date: 2019-04
• Subjects: Optical gas cell -- Absorption spectroscopy -- High-temperature -- High-pressure -- Mid-wave infrared; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2019.01.029
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: Optical gas cell design for absorption spectroscopy studies at extreme conditions. CaF2 optics enable mid-wave IR measurements up to 8 µm at both > 100 atm and > 1000 K. Evidence of line mixing and undocumented transitions observed in ν 4 band of CH4 . Abstract: An optically accessible gas cell has been designed, manufactured, and tested for the purpose of enabling spectroscopic measurements in the mid-wave infrared at both high pressures and high temperatures. The water-cooled inconel cell has been tested to sustain pressures over 200 atm or operating temperatures above 1200 K. Interchangeable sapphire or calcium-fluoride rods, transmissive up to 8 µm in wavelength, are used to span the thermal gradients at the edge of the heating zone, providing for a low-temperature seal on one end and access to a thermally uniform test section on the other. In this paper, we detail the cell design and validation testing, while highlighting cell capabilities with laser absorption measurements of gas spectra in the 2–8 µm domain at high-pressure ( > 100 atm) and high-temperature ( > 1200 K) conditions. The maximum cell pressure and temperature reached simultaneously was 102 atm and 1030 K. Non-ideal spectroscopic phenomena (e.g. line mixing) are revealed at the extreme conditions investigated.