Characterization of the New UCR Fixed-volume Chamber
QI LI, Thomas Eckel, Chen Le, Huawei Li, Sahar Ghadimi, Ryan W. Drover, Daniel Gonzalez, David R. Cocker III,
University of California, Riverside Abstract Number: 493
Working Group: Aerosol Physics
AbstractStatic electric charges have been identified to be the most critical factor impacting the previous-generation UCR dual collapsible chamber systems with respect to particle-wall interactions. The new generation UCR chamber system (~120 m
3 fixed volume) was finished in 2021. The chamber is suspended, electrically isolated from other surfaces, and equipped with three soft x-ray photoionizers to discharge the chamber before each experiment leading to a highly consistent surface static charge status (surface voltage within ±10V) across experiments. The chamber was measured to have an extremely low PM background of <0.01 μm
3/cm
3 after 8 hours of irritation with 2 ppm H
2O
2. Low particle total number decay rates <2 day
-1 were achieved with the low static charge and low chamber surface area to volume ratio (1.22m
-1). An upgraded three-component particle loss correction method was developed and validated to have ~100% recovery rate in pure seed deposition experiments. Detailed characterization of the new chamber will be provided and compared to the UCR dual collapsible chamber system, including geometry, soft x-ray setup configuration, surface charging measurements, UV lights profiles, dilution ratios, etc. Advanced understanding on particle deposition rate and vapor wall loss will be presented as well with discussions on varying factors that can significantly affect vapor wall loss.