Temperature uniformity in the CERN CLOUD chamber
The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN (European Council for Nuclear Research) investigates the nucleation and growth of aerosol particles under atmospheric conditions and their activation into cloud droplets. A key feature of the CLOUD experiment is precise control of the...
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doaj-f682becc352840caabdc2c97113ed7f32020-11-25T00:42:27ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482017-12-01105075508810.5194/amt-10-5075-2017Temperature uniformity in the CERN CLOUD chamberA. Dias0S. Ehrhart1S. Ehrhart2A. Vogel3A. Vogel4C. Williamson5C. Williamson6C. Williamson7J. Almeida8J. Almeida9J. Kirkby10J. Kirkby11S. Mathot12S. Mumford13S. Mumford14A. Onnela15CERN, 1211 Geneva, SwitzerlandCERN, 1211 Geneva, Switzerlandnow at: Max Planck Institute for Chemistry, Atmospheric Chemistry Department, Hahn-Meitner-Weg 1, 55128 Mainz, GermanyCERN, 1211 Geneva, Switzerlandnow at: Paul Scherrer Institute, Aarebrücke, 5232 Villigen, SwitzerlandGoethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, 60438 Frankfurt am Main, Germanynow at: Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, CO, USAnow at: CIRES, University of Colorado, Boulder, CO, USACERN, 1211 Geneva, SwitzerlandGoethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, 60438 Frankfurt am Main, GermanyCERN, 1211 Geneva, SwitzerlandGoethe University Frankfurt, Institute for Atmospheric and Environmental Sciences, 60438 Frankfurt am Main, GermanyCERN, 1211 Geneva, SwitzerlandCERN, 1211 Geneva, Switzerlandnow at: Kapitulink Lab, 476 Lomita Mall, Stanford University, Stanford, CA 94305-4045, USACERN, 1211 Geneva, SwitzerlandThe CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN (European Council for Nuclear Research) investigates the nucleation and growth of aerosol particles under atmospheric conditions and their activation into cloud droplets. A key feature of the CLOUD experiment is precise control of the experimental parameters. Temperature uniformity and stability in the chamber are important since many of the processes under study are sensitive to temperature and also to contaminants that can be released from the stainless steel walls by upward temperature fluctuations. The air enclosed within the 26 m<sup>3</sup> CLOUD chamber is equipped with several arrays (<q>strings</q>) of high precision, fast-response thermometers to measure its temperature. Here we present a study of the air temperature uniformity inside the CLOUD chamber under various experimental conditions. Measurements were performed under calibration conditions and run conditions, which are distinguished by the flow rate of fresh air and trace gases entering the chamber at 20 and up to 210 L min<sup>−1</sup>, respectively. During steady-state calibration runs between −70 and +20 °C, the air temperature uniformity is better than ±0.06 °C in the radial direction and ±0.1 °C in the vertical direction. Larger non-uniformities are present during experimental runs, depending on the temperature control of the make-up air and trace gases (since some trace gases require elevated temperatures until injection into the chamber). The temperature stability is ±0.04 °C over periods of several hours during either calibration or steady-state run conditions. During rapid adiabatic expansions to activate cloud droplets and ice particles, the chamber walls are up to 10 °C warmer than the enclosed air. This results in temperature differences of ±1.5 °C in the vertical direction and ±1 °C in the horizontal direction, while the air returns to its equilibrium temperature with a time constant of about 200 s.https://www.atmos-meas-tech.net/10/5075/2017/amt-10-5075-2017.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
A. Dias S. Ehrhart S. Ehrhart A. Vogel A. Vogel C. Williamson C. Williamson C. Williamson J. Almeida J. Almeida J. Kirkby J. Kirkby S. Mathot S. Mumford S. Mumford A. Onnela |
spellingShingle |
A. Dias S. Ehrhart S. Ehrhart A. Vogel A. Vogel C. Williamson C. Williamson C. Williamson J. Almeida J. Almeida J. Kirkby J. Kirkby S. Mathot S. Mumford S. Mumford A. Onnela Temperature uniformity in the CERN CLOUD chamber Atmospheric Measurement Techniques |
author_facet |
A. Dias S. Ehrhart S. Ehrhart A. Vogel A. Vogel C. Williamson C. Williamson C. Williamson J. Almeida J. Almeida J. Kirkby J. Kirkby S. Mathot S. Mumford S. Mumford A. Onnela |
author_sort |
A. Dias |
title |
Temperature uniformity in the CERN CLOUD chamber |
title_short |
Temperature uniformity in the CERN CLOUD chamber |
title_full |
Temperature uniformity in the CERN CLOUD chamber |
title_fullStr |
Temperature uniformity in the CERN CLOUD chamber |
title_full_unstemmed |
Temperature uniformity in the CERN CLOUD chamber |
title_sort |
temperature uniformity in the cern cloud chamber |
publisher |
Copernicus Publications |
series |
Atmospheric Measurement Techniques |
issn |
1867-1381 1867-8548 |
publishDate |
2017-12-01 |
description |
The CLOUD (Cosmics Leaving OUtdoor Droplets) experiment at CERN (European Council for Nuclear Research) investigates the nucleation and growth of aerosol particles under atmospheric conditions and their activation into cloud droplets. A key feature of the CLOUD
experiment is precise control of the experimental parameters. Temperature
uniformity and stability in the chamber are important since many of the
processes under study are sensitive to temperature and also to contaminants
that can be released from the stainless steel walls by upward temperature
fluctuations. The air enclosed within the 26 m<sup>3</sup> CLOUD chamber is
equipped with several arrays (<q>strings</q>) of high precision, fast-response
thermometers to measure its temperature. Here we present a study of the air
temperature uniformity inside the CLOUD chamber under various experimental
conditions. Measurements were performed under calibration conditions and run
conditions, which are distinguished by the flow rate of fresh air and trace
gases entering the chamber at 20 and up to 210 L min<sup>−1</sup>,
respectively. During steady-state calibration runs between −70 and
+20 °C, the air temperature uniformity is better than
±0.06 °C in the radial direction and ±0.1 °C in the
vertical direction. Larger non-uniformities are present during experimental
runs, depending on the temperature control of the make-up air and trace gases
(since some trace gases require elevated temperatures until injection into
the chamber). The temperature stability is ±0.04 °C over periods
of several hours during either calibration or steady-state run conditions.
During rapid adiabatic expansions to activate cloud droplets and ice
particles, the chamber walls are up to 10 °C warmer than the
enclosed air. This results in temperature differences of ±1.5 °C
in the vertical direction and ±1 °C in the horizontal direction,
while the air returns to its equilibrium temperature with a time constant of
about 200 s. |
url |
https://www.atmos-meas-tech.net/10/5075/2017/amt-10-5075-2017.pdf |
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