Performance of pure tungsten and tungsten fiber-reinforced tungsten composites exposed to various simulated ELMing conditions

Tungsten (W) has been chosen as the main plasma facing material for ITER due to its favorable thermal and mechanical properties. However, W suffers from a high brittle to ductile transition temperature and is prone to cracking under high thermal stresses. To combat catastrophic cracking in future DEMO reactors, W fiber-reinforced W composites (W_f/W), fabricated at FZJ-IEK, are investigated for increased mechanical strength and fracture toughness. Previous results have investigated plasma erosion, deuterium retention, and RT thermal shock testing. This study aims to further investigate W_f/W exposed to a wider range of simulated type-1 edge localized modes (ELMs) using our CMUXE Ultra-High Flux Irradiation Chamber (UHFI-II). The UHFI-II chamber is equipped with steady state heating up to 1473 K, two end hall ion sources utilizing D⁺ and He⁺ with energies ~40 – 200 eV, and a pulsed millisecond Nd:YAG laser with average power up to 6.0 kW. Simulated ELM experiments are conducted for one hour at various base temperatures with featured ion ratios of 100:0|He:D and 10:90|He:D (reactor condition) at combined fluences of 1.08 × 10²³ and 2.16 × 10²³ ion m^-2 respectively. Transient laser heating is focused to ~2 mm diameter spot size and tuned from a pulse duration of 0.2 – 10 ms with pulse frequencies of 1 – 30 Hz. Various experiments are currently being conducted relating to approximate Type-1 ELM conditions (0.1 – 5 ms @ 1 – 5 Hz). Analysis of damage and erosion is underway using extensive microscopy and spectroscopy techniques.