Characterization of Dust and Debris Collected from the Nova Facility

Dust and debris were collected from the Nova laser facility in April 1999 to provide evidence of particulate generation and transport mechanisms relevant to fusion power safety analyses. Samples were obtained at specified locations within the Nova chamber with a vacuum filter system, cascade impactors, and metallurgical replicating tape (acetate tape). Average surface mass density of material collected from locations with measured surface area ranges from 3.13 μg/cm² on the mid-plane vertical surface to 3250 μg/cm² on the vessel bottom. Estimated total dust inventory is 44 grams. Specific surface area of dust collected from several locations is nearly uniform with an average value of 0.435 m²/g. Particle size distributions of the collected material show a range of count median diameters (CMD) between 0.67 and 1.19 μm with geometric standard deviations (GSD) between 1.63 and 2.76. Mass median diameters for dust collected with the two cascade impactors are 5.26 μm and 8.85 μm. The shape of the volumetric size distribution indicates dust particles of various shapes. Composition analysis performed by energy dispersive X-ray analysis indicated the presence of O, Al, Cu, along with trace quantities of Fe, Au, and Be. Atomic emission ICP analysis also indicated the presence of Si, O, and Cu in dust samples.