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During the normal operation and maintenance activities of a fusion device, particulate (dust) are produced within the device's plasma chamber. Such particulate may be toxic, radioactive, and/or chemically reactive. The general hazards of tokamak dust are related to the dust composition, total dust mass and surface mass density distributions, and total dust surface area. Understanding the mechanisms that generate the dust and correctly describing the dust's physical and chemical behavior is essential for the safety analyses of fusion devices.

Our research on the mobilization of tokamak dust focuses on studying the physical characteristics (size and effective surface area) of the particulate. The particulate are studied by using our Tokamak Dust Laboratory (TDL), a facility dedicated to the physical characterization of dust particles from tokamak devices. This laboratory is used for various analyses and observations after the particles have been obtained from experimental fusion devices. Figures 1 through 3 present dust/debris from the Tokamak Fusion Test Reactor (Princeton Plasma Physics Laboratory), DIII-D (General Atomics), Alactor C-MOD (Massachusetts Institute of Technology), Tore Supra (CEA-Cadarache), and NOVA (Lawrence Livermore National Laboratory) that were characterized in the TDL.

Figure 1: Dust Characterization of TFTR, DIII-D and C-MOD

Figure 2: Dust Characterization of Tore Supra

Figure 3: Dust Characterization of NOVA

The particle sizes were characterized based on analyses from:

• laser-based sizing system
• high magnification microscopy
• scanning electron microscopy (SEM)
• mass based aerosol detection
• count based aerosol detection

The surface area of a dust particle is examined by using the Brunauer, Emmett, and Teller (BET) analysis technique with data from an accelerated surface area and porosimetry (ASAP) instrument. Chemical characterization of the dust particles is accomplished by using SEM/Energy Dispersive Spectroscopy (EDX), Inductively-Coupled Mass Spectroscopy (ICP-MS), and Inductively-Coupled Atomic Emission Spectroscopy (ICP-AES).