The experiment will utilize the Divertor Material Exposure Station (DiMES) in the DIII-D tokamak to expose small samples of advanced tungsten materials exclusively to ELMy H-mode plasmas.
The materials to be tested include:
1. Dispersoid-Strengthened Tungsten (DSW) with transition metal carbides (e.g., TaC, TiC, ZrC).
2. Tungsten-based Multiple Principle Element Alloys (MPEAs) such as W-Mo-Nb-Ta, W-Cr-V, and W-Ta-Ti.
3. Tungsten Heavy Alloys (WHA) containing Ni, Cu, or Fe.
4. Tungsten composites reinforced with SiC fibers (Wf/W, SiC/W, and SiC-W/W).
5. Plasma-sprayed tungsten coatings (PS-W).
The DiMES probe will be used to expose these materials to high heat and particle fluxes to simulate the conditions of a fusion reactor divertor. The experimental setup will involve multiple DiMES heads with flush and angled samples, subjected to high-power H-mode discharges with ELMy conditions to maximize the assessment of erosion, thermal resilience, and surface morphology changes.
Key aspects of the experimental approach include:
● DSW Samples: Various compositions with optimized microstructures and pre-implanted with helium to investigate the impact of thermal shock events, recrystallization, and erosion under H-mode conditions.
● MPEA Samples: Investigation of preferential sputtering, erosion rates, and hydrogen retention to determine the effects of alloy composition on material performance.
● WHA Samples: Evaluation of the ductility and thermal fatigue resistance under high heat flux conditions.
● Tungsten Composites: Testing of crack propagation, pseudo-ductility, and thermal performance of SiC fiber-reinforced tungsten composites.
● Plasma-Sprayed Coatings: Assessment of the resilience and performance of in-situ plasma-sprayed tungsten coatings under high heat flux conditions.
Post-exposure analyses will include scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), thermal desorption spectroscopy (TDS), and various spectroscopic techniques to evaluate surface damage, composition changes, and deuterium retention. The results will inform the optimization of tungsten-based materials for improved performance in the extreme environment of a fusion reactor. By integrating these diverse approaches, this experiment aims to provide a comprehensive understanding of the performance and optimization potential of advanced tungsten-based materials for future fusion reactors.
