Developing A Custom-Built Metal Aerosol Processing Chamber: Analysis of Aerosol Coagulation at Low Humidities

<p>We have developed an intermediate size (906 L) aerosol processing chamber, and this work reports on the design and initial characterization of dry aerosol experiments. Specifically, we are determining wall-loss and coagulation correction factors using the observed size distribution measurements for surrogates of common aerosol classes: sodium chloride, sucrose, and biomass burning aerosol smoke. Results show that, on average, sodium chloride, sucrose, and smoke wall-loss rates converge to similar values on relatively short time scales (<span class="inline-formula"><i>&lt;</i></span> 1 h). The fitted coagulation correction factor, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi>W</mi><mi mathvariant="normal">C</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="95e0043826b3994938eca2cc433f4b7a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-18-5705-2025-ie00001.svg" width="23pt" height="17pt" src="amt-18-5705-2025-ie00001.png"/></svg:svg></span></span>, for smoke particles (1.23 <span class="inline-formula">±</span> 0.312), indicates that on average they adhere to each other more than sodium chloride (0.969 <span class="inline-formula">±</span> 0.524) and sucrose (1.16 <span class="inline-formula">±</span> 1.38). The relative uncertainty is high for the coagulation correction, but it is consistent with our Monte Carlo error analysis. This study lays the foundation for future experiments at elevated humidity and supersaturation conditions to characterize the influence of particle shape on coagulation and cloud parameters.</p>