COLD 2
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COLD (Carbon Monoxide Laser Detector) 2 is a gas analyzer, tailored for the measurement of ambient carbon monoxide from the ground up to stratosphere, where the mixing ratio can drop down to a few ppb.
It is based on the absorption of radiation at 4.7 micron, emitted by a room temperature Quantum Cascade Laser, iside a multipass cell, 36 m pathlength.
It is the evolution of the instrument COLD (Cryogenically Operated Laser Diode). In that case the laser was a lead salts laser, operating at temperatures slightly above Liquid Nitrogen boiling temperature. In the photo below, the central plastic disk is the cover of the LN Dewar.
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The change from cryogenic laser to room temperature laser was accompanied by a complete revision of the electronics, so that the dimensions and weight were substancially reduced.
The instrument was originally designed to be deployed onboard M55 “Geophysica” aircraft (1500 kg payload, 21.000 m ceilings height).
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It was recently adapted to fly onboard a Zero Pressure Balloon, up to 34 km height.
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At the moment it is under restyling, in order to be deployed onboard NASA WB-57, for the ACCLIP campaign.
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References:
S. Bucci, B. Legras, P. Sellitto, F. D’Amato, S. Viciani, A. Montori, A. Chiarugi, F. Ravegnani, A. Ulanovsky, F. Cairo, and F. Stroh: “Deep convective influence on the UTLS composition in the Asian Monsoon Anticyclone region: 2017 StratoClim campaign results”, Atmos. Chem. Phys. 20, 12193-12210 (2020), doi: 10.5194/acp-20-12193-2020
S. Viciani, A. Montori, A. Chiarugi and F D’Amato: “A Portable Quantum Cascade Laser Spectrometer for Atmospheric Measurements of Carbon Monoxide”, Sensors 18, 2380 (2018), doi: 10.3390/s18072380
S. Viciani, F. D’Amato, P. Mazzinghi, F. Castagnoli, G. Toci, P.W. Werle: “A cryogenically operated laser diode spectrometer for airborne measurement of stratospheric trace gases”, Appl. Phys. B 90, pp. 581-592 (2008), doi: 10.1007/s00340-007-2885-2