AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
A Compact, “MAGIC” Water Condensation Particle Counter
STEVEN SPIELMAN, Gregory Lewis, Arantzazu Eiguren Fernandez, Jocelyn Bale-Glickman, David Delew, Susanne Hering, Aerosol Dynamics Inc.
Abstract Number: 639 Working Group: Instrumentation and Methods
Abstract A fully integrated, self-sustaining, water-based condensation particle counter has been developed and validated. Called MAGIC, for moderated aerosol growth with internal water cycling, this instrument obtains the water needed for condensational growth through a combination of capture of water vapor from the sampled air, and internal recapture of water vapor after particle activation. Recent efforts have focused on refining and testing a fully integrated system, with the aim to provide a robust system. A Nafion-based sample stream humidifier has been added to partially humidify the incoming air stream so as to guarantee sufficient water vapor to sustain operation over multiple weeks of operation. System temperatures are adjusted based on the measured temperature and relative humidity at the growth tube inlet, which enables stable multi-week operation. A new optical detector has been designed that uses a longer focusing path, a wider beam waist and a larger diameter focusing nozzle to reduce the sensitivity to accumulated debris in the nozzle or slight misalignment of optics. Calibrations were done with reference to the versatile water-based condensation particle counter (Hering et al, 2017), which is independently calibrated against an aerosol electrometer. Laboratory-generated sulfate and sucrose aerosols show that the lower threshold for particle detection is below 7 nm. It has a rather gentle response curve, rising to 80% detection efficiency at 14 nm, 90% detection at 28 nm, and above 95% for particles larger than 40 nm. The measured response is linear with concentration up to the highest levels tested which were 105/cm3.