CESAM

The CESAM platform consists of a combination of two chambers (CESAM chamber and CSA chamber) that can work both with gas or multiphase reacting mixtures involving gaseous trace species, organic particles, water droplets, mineral dust, soot and salts. It has been designed to perform studies on multiphase atmospheric processes under realistic conditions.

The CESAM chamber is the largest atmospheric simulation chamber of the CESAM platform. It is dedicated to the study of multiphase atmospheric processes such as the formation of secondary aerosol or gaseous compounds in cloud-phase reactivity. It’s a 4.2 m3 stainless steel atmospheric simulation chamber, evacuable down to a few 10-7 atm and it is temperature controlled between +0°C and +60°C. It is equipped with high power xenon arc lamps which the artificial light source the more realistic to sun irradiation. Due to the very low level of electrostatic charges on its wall the aerosol lifetime in CESAM can be very long for submicron particle (up to 4 days) which enable the study of the ageing processes of secondary aerosol as well as their consequences on their properties. The scientific spectrum of CESAM chamber is nevertheless much larger than SOA studies as it is also possible to generate cloud events, to inject desert dust or soots, to seed with ionic aerosols and to perform photochemistry study. CESAM chamber is granted by CNRS as national instrument.

The CSA chamber is an atmospheric simulation chamber dedicated to the atmospheric gas processes and spectrometry studies. It is a 1m3 pyrex reactor evacuable down to a few 10-2 mbars. It is equipped with artificial irradiation system which consist in 80 UV-lamps (centred at 360 nm and 420 nm) and 16 arc and Hg lamps (λ < 300 nm). The CSA is equipped with analytical devices for gas phase such asUV-Visible and Visible IBB-CEAS spectrometer, FTIR and PTR-Tof-MS (Kore ltd.) that enable atmospheric chemistry monitoring and cross-determination of compound absorptivities in both IR and UV-Visible spectral ranges withnumerous applications for remote sensing measurements. The CSA chamber is a perfect tool for intercalibration of IR/UV spectra and study the gas phase reactivity of organic and polyfunctional organic species (e.g nitrates). It is a complementary glass chamber which offers a good alternative to stainless steel walls. 

The CESAM platform is equipped with a comprehensive set of analytical instruments and benefits from the instrumental environment dedicated to atmospheric chemistry provided by LISA: PTR-ToF-MS (Kore ltd.), NOx Analyser, O3 Analyser, SO2 Analyser, External CRDS (Picarro 2302), Sorbent cartridges + GC-MS, Automatic GC- FID, in-situ FTIR, Hygrometer, Supercritical Fluid Extraction- GC-MS, EC/OC (Sunset), Hygroscopy Tandem DMA, Analytical Electron microscopes, SMPS, Light-scattering aerosol, CAPS-Pmex Aerodyne, CAPS-Pmex Aerodyne, Nephelometre (TSI 3596), Aethalometer (AE-31 Magee Scientific), Spectroradiometer LiCOR 1800.

Features that make it rare in the world:
- Very long submicronic aerosol lifetime
- Ability to produce clouds
- Protocol for mineral dust seeding
- Temperature control and highly realistic artificial solar irradiation - high cleanliness level
- Quality of the instrumentation

The services offered by the infrastructure include:

-  Access to the full equipment of the CESAM platform to which can be added when possible the equipment of the Pegasus field facility as well as the clean rooms, two electron microscopes (TEM, SEM)
-  Technical assistance by a staff of highly trained engineers
-  Scientific assistance (including protocol definition and pre-modelling) by permanent researcher at LISA
-  Copy of all the level 0 data at the end of the campaign
-  Data treatment up to level 1 when requested
-  Data saving (>10 years) on the highly secured LISA computer facility
-  Guest office for up to 4 guests and internet access
-  150 m2 lab at ground floor allowing easy access to heavy guest instrument (travelling crane up to 2000 kg available)
-  24h access to the lab if requested support for ordering chemicals and consumables,...

Between 1 and 3 weeks. A typical work includes 2-3 days to carefully prepare the experiments (latest protocol adjustment, connection of potential external instruments, and training on the use of the chamber and the main devices), then 10 days of experiments (1 experiments/day), then 1-2 days for debriefing and base data formatting, saving, and distributing among the users. 

The CESAM platform is mainly used for research project (so academic sector) nevertheless we have had experiment conducted with companies (self-cleaning material) and for protocol testing from governmental agency (INERIS).
We believe that we will increase our penetration of the sensors/instrumentation community.

Reactions                                                     constants                                   Note

NO₂ → NO_{2_Wall}                                             2.2.10^-3 s^-1                                      Indicative value only

NO₂_Wall → NO₂                                          1.0.10^-1 s^-1                                        Indicative value only

NO₂ D NO_{2_Wall}                                                46                                         Fast equilibrium : only the ratio k₅/k_-6 was determining

NO_{2_Wall} → α NO + β HONO               2.0.10^-3 s^-1                                     α = 0.34 and β = 0.07

NO_{2_Wall} + hv → δ NO + γ HONO      1.4.10^-2 s^-1                                       δ = 0.51 and γ = 0.10

O₃ → O_{3_Wall}                                                     3.0.10^-4 s-1