Collection and analysis of particulate from the DIII-D Tokamak

Particulate (i.e. Tokamak dust) has been collected from the DIII-D Tokamak located at General Atomics in San Diego, CA, USA. Two methods were used to collect particulate with the goal of preserving the particle size distribution and physical characteristics of the particulate. Vacuum collection on substrates and adhesion removal with metallurgical replicating tape were chosen as non-intrusive sampling methods. Sampling was completed in four toroidal locations of the machine; the 0–90° area, the 90–180° area, the 180–270° area, and the 270–360° area. The 0° direction designates the north side of the DIII-D machine. Four tiles in each area were sampled; the first vertical tile above the floor on the centerpost, a floor tile next to the center post, a tile on the isolated ring, and the first tile up from the isolated ring on the divertor. In addition, samples were collected from underneath the floor tiles at the 275 and the 75° locations. The count median diameter of the samples ranged from 0.50 to 0.86 μm, with geometric standard deviations ranging from 2.0 to 3.5. Diameters of average mass calculated from Hatch–Choate equations based upon log normal distribution characteristics ranged from 2.8 to 7.5 μm.