Miniature fast response CCN counter

There is an increasing need to understand the impacts particles emitted by both natural and human activities have on cloud properties, precipitation and climate. DOE has identified a need to improve the measurement capability of observational platforms, particularly in the Arctic region. One barrier to progress in understanding the interactions of particles and clouds and the importance of cloud condensation nuclei has been limited observations, particularly in remote regions. Unmanned aerial vehicles represent a potentially powerful tool for providing much more frequent observations of cloud condensation nuclei, but require instrumentation that operates autonomously, requires little power or space, and is lightweight. The objectives of the proposed project are to build and test two new growth chamber designs for integration into test beds that will provide rapid, accurate measurements of cloud condensation nuclei concentrations at a range of supersaturations (design range 0.02-1%). The designs will be lightweight, small, and require low power consumption and will therefore be suitable for deployment on unmanned aerial vehicles to provide autonomous measurements of cloud condensation nuclei in remote regions. Phase I work includes design of a short cylindrical growth chamber column with flow rate and temperature gradient control, manufacture of the growth chamber, integration with existing control and activated droplet detection hardware, and laboratory testing of the prototype designs. Phase I work also includes design and testing of a novel flared growth chamber that provides a constant pressure drop along the growth chamber and is a new method for generating and controlling supersaturation within the growth tube that does not require temperature control, greatly simplifying the burden for a environments where weight, power and size are critical. Commercial applications and benefits include wider availability and utility for cloud condensation nuclei measurements critical to understanding impacts of human and natural activities on clouds, precipitation, the hydrological cycle and climate. The wider availability and utility would result from reduced power, weight and size of the instrument, opening up new platforms for cloud condensation nuclei measurements, and an anticipated lower cost for the measurement system due to its reduced complexity compared to the highly successful DMT CCN-100 and -200 series of instruments.