Abstract Number: 662 Working Group: Instrumentation and Methods
Abstract A newly-developed, versatile water condensation particle counter (vWCPC) capable of near 1nm particle detection was deployed at the Southern Great Planes Atmospheric Radiation Measurement Site during August and September, 2016. Measurements were made as part of the Hi-SCALE program, with a focus on the formation of new particle formation. The vWCPC (Hering et al, Aerosol Science and Technology, 2017) provides particle detection near 1nm at an aerosol flow of 0.3L/min, without use of a sheath. It employs a three-stage, laminar-flow growth tube. The temperature difference between the first two stages is user-selectable, and determines the peak supersaturation, and hence the lower particle activation size. The cooled third stage maintains supersaturated conditions that permit continued droplet growth while reducing the temperature and water content of the flow prior to particle counting. This approach makes feasible operation at the large temperature differences necessary for high supersaturations and small particle detection. This new growth tube was mounted in the box from a TSI Model 3787 WCPC, and operated with the TSI optics and mother board. Operating temperatures are flexible, and can be chosen either to maximize particle detection near 1 nm, or to eliminate sensitivity to charger ions. For the HiSCALE field study the latter mode of operation was used, which provides 50% detection at 1.8nm. Data are compared to parallel measurements with a TSI Model 3776.