2025 – Plasma Exposure of Pre-Irradiated Materials in DiMES

Plasma Exposure of Pre-Irradiated Materials in DiMES

2025 Research Campaign, Thrust: FPP Candidate Wall Materials

Purpose of Experiment

Novel and/or advanced plasma-facing materials must be investigated for use in next-generation fusion devices. This experiment in DIII-D aims to characterize the plasma-material interaction (PMI) response of fusion pilot-plant (FPP) relevant material candidates by exposing them to tokamak plasma using the Divertor Materials Evaluation System (DiMES). Materials to be exposed are pristine and neutron irradiated monolithic silicon carbide (SiC), titanium diboride (TiB2), titanium carbide (TiC), tungsten (W), and potassium doped tungsten (K-doped W). These samples will be exposed to L-mode plasma to characterize how neutron damage influences plasma-induced defect evolution and hydrogen isotope retention in the materials. In most FPP magnetically confined fusion device concepts, material degradation from neutron is inevitable; it is vital to characterize how neutron damage impact plasma response of fusion first wall materials.

Experimental Approach

TiC, TiB2, W, and K-doped W samples were exposed to fission neutron spectra from the High Flus Isotope Reactor (HFIR) located in ORNL. The ceramic TiC and TiB2 samples were irradiated at 1000*C and exposed to 10 dpa neutron doses. The W and K-doped W samples were irradiated at 850*C and exposed to 0.5 dpa neutron doses. These samples and pristine counterparts of the materials will be exposed to L-mode plasma using the DiMES system. Shot 200682 will be used as a reference shot. Two DiMES heads will be used; one cap filled with the ceramic samples and another filled with the W-based materials. Step one includes bringing up the reference shot and running it with the DiMES head recessed to establish background spectroscopy data and ensure acceptable heat fluxes applied on the samples. After the reference discharge is established, the first DiMES head containing the ceramic samples will be brought up and exposed repeated discharges to build up a high deuterium fluence in the samples. After half of the runtime is completed, the second DiMES cap containing the tungsten samples will be loaded into DiMES. These samples will then be exposed to identical conditions as the first DiMES cap to facilitate direct comparisons of the all the materials across the separate DiMES head. After exposures, post-mortem analysis of the samples will be performed to measure defect accumulation and type as well as deuterium retention in the samples.

Interested in learning more about how engagement with DIII-D benefits the fusion industry and supply chain? Join us for the DIII-D Industry Event Day on Nov. 14th! Registration and further information can be found here.

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