Ion Microbeam Analyses of Dust Particles and Codeposits from JET with the ITER-Like Wall

Generation of metal dust in the JET tokamak with the ITER-like wall (ILW) is a topic of vital interest to next-step fusion devices because of safety issues with plasma operation. Simultaneous Nuclear Reaction Analysis (NRA) and Particle-Induced X-ray Emission (PIXE) with a focused 4 MeV 3He micro-beam was used to determine the composition of dust particles related to the JET operation with the ILW. The focus was on ‘Be-rich particles’ collected from the deposition zone on the inner divertor tile. The particles found are composed of a mix of co-deposited species up to 120 µm in size with a thickness of 30-40 µm. The main constituents are D from the fusion fuel, Be and W from the main plasma-facing components, and Ni and Cr from the Inconel grills of the antennas for auxiliary plasma heating. Elemental concentrations were estimated by iterative NRA-PIXE analysis. Two types of dust particles were found: (i) larger Be-rich particles with Be concentrations above 90 at% with a deuterium presence of up to 3.4 at...