A Wide Range, Multi-Angle, Light Scattering Device to Probe Hazardous Aerosol Particles

RAIYA EBINI, Joshua Hubbard, Christopher M. Sorensen, Alex Brown, Joseph Zigmond, Sandia National Laboratories

     Abstract Number: 696
     Working Group: Instrumentation and Methods

Abstract
In past work, a unique combustion chamber was designed to capture soot from small liquid and solid waste fires designed to mimic nuclear waste [1],[2]. It was found that the mass of hazardous contaminants released was not directly proportional to the mass of the material consumed by fire [1],[2]. The size and morphology of these particles are important factors in respiratory health assessments. Our goal is to provide in-situ, real-time, characterization of aerosols that contain hazardous contaminants. We have built a wide range, multi-angle, light scattering device to accomplish this goal. The optical design adopted here is primarily influenced by the design of Guatum and Sorensen [3]. Our new apparatus can probe three separate scattering regimes: forward, back, and side scattering. Combining these regimes is important to provide a complete understanding of scattering by aerosol particles [4].

In preliminary experiments we integrated the combustion chamber with a small angle light scattering apparatus. This allowed us to characterize the forward scattering regime. Soot aggregates released from burning kerosene, and other contaminated flammable mixtures, were characterized. Soot aggregates were investigated within the luminous flame as well as after it left the chamber as smoke. The size of soot aggregates within the flame was 0.5µm whereas in the smoke it was 7.5µm.

Our new, four detector apparatus is designed to accomplish the following goals: simultaneously probe the three scattering regimes, study soot aggregates inside and outside the flame simultaneously, and accommodate hazardous materials like depleted uranium. This poster shows the design and calibration for this device. The apparatus contains two forward scattering detectors designed to probe the soot inside and outside the flame. Each scattering regime has a designated detector. Calibration methods have been developed and are outlined here.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.