CFDC-IAS - Handix Scientific Inc.

CFDC-IAS

Continuous Flow Diffusion Chamber - Ice Activation Spectrometer

Purpose

The Continuous Flow Diffusion Chamber - Ice Activation Spectrometer (CFDC-IAS) provides real-time measurements of ice-nucleating
particle (INP) concentrations under well-defined temperature and supersaturation conditions.

Building upon the well-established and
published Colorado State University CFDC
design, the CFDC-IAS has a proven record of successful deployments in aircraft, laboratory, and extended field campaigns worldwide.

Operational Models of CFDC-IAS:
CFDC-IAS-G: Default model of CFDC-IAS offered. Model number is interchangeable with CFDC-IAS.
CFDC-IAS-M: Upon special request and non-standard, Handix Scientific can also manufacture Airborne or Mobile models customized for application, labeled with '-M'.

CFDC-IAS-G Model. Sample aerosol are dried and sampled into the top of the processing chamber, where they are exposed to user-controlled temperature and relative humidity conditions. INP form ice crystals that are detected optically at the base of the chamber.

Applications:

Laboratory INP characterization
Field ambient INP measurement
Aerosol-cloud interactions
Climate research
Weather modification and cloud seeding

INP measured during a 24-hour period in Beijing by a CFDC-IAS operating autonomously. The CFDC-IAS operated for approximately 6 weeks with minimal user intervention before being relocated to a new site in late June 2018. Gaps in INP data result from melting and re- icing measurement chamber to maintain sensitivity.

Features

Cylindrical processing chamber to minimize edge-effects
Measurement range approximately -10 to -40 C and RH 80-108%.
Liquid-based refrigeration system provides excel- lent temperature stability and uniformity
Approximately 1 L-1 measurement sensitivity
Automation & system upgrades that support autonomous, long-duration measurements with stable performance and low background

Specifications

Operating Principle

The CFDC-IAS exposes sampled aerosol particles to controlled temperature and water saturation conditions found in mixed-phase clouds. It features two ice-coated cylindrical walls that are kept at different temperatures to drive temperature and water vapor pressure gradients between them. The different rates of diffusion for water vapor and heat lead to a region between the walls that is super-saturated with respect to ice, and depending on the magnitude of the gradient, water. Aerosol passing between the walls freeze either directly as ice crystals (deposition freezing) or first activate as a super-cooled liquid droplet, which may then freeze (condensation/immersion freezing). Ice crystals formed in the chamber are counted with an optical particle counter at the exit of the chamber.

Simplified diagram of the CFDC-IAS measurement chamber showing concentric arrangement of ice-covered cold inner and warm outer walls (left) and illustration showing growth of droplets and ice crystals in different sections of the chamber (right). Only large crystals and small aerosols reach the OPC.

Petters, M. D., et al., Ice nuclei emissions from biomass burning, Journal of Geophysical Research, doi:10.10292008JD011532, 2015.

Bi, K., et al., Measurements of ice nucleating particles in Beijing, China, Journal Geophysical Research: Atmospheres, 2019.

Visit handixscientific.com/references/ for more CFDC publications.

Reference:

Particle Size Range	Depends on upstream impactor, usually all particles up to 1-2.5 μm
Sensitivity and Range	1-sigma limit of detection at 300 s; 1 L-1
Flow and Response Time	Sample flow: 1.5 LPM Response time: ~1-5 minutes
Environmental Operating Conditions	Min. Temperature 5 C Max. Temperature 30 C Ambient Humidity: non-condensing
Data Logging and Storage	Stores data on integrated control and acquisition PC with 256GB storage, sufficient for many months.
Required Consumables	Purge gas: Nitrogen @ 15 PSI Icing liquid: DI water (~4 L) Cooling liquid: ethanol (~12 L)
Power Requirements	AC power: 110-230 VAC, 50/60 Hz Power consumption 6000 W (peak)
Communications	Ethernet Interface: 8-wire, RJ-45, 10/100 BASE-T, TCP/IP
Physical Dimensions	Instrument. 21 x 28 x 50 in +chillers Weight ~100 kg +chillers

Specifications subject to change without notice.