Articolo in rivista, 2023, ENG, 10.1016/j.nme.2023.101422

Study the erosion of Eurofer-97 steel with the linear plasma device GyM

Uccello A.; Ghezzi F.; Kovac J.; Ekar J.; Filipic T.; Bogdanovic Radovic I.; Dellasega D.; Mellera V.; Pedroni M.; Ricci D.; GyM Team

CNR ISTP - Istituto per la Scienza e Tecnologia dei Plasmi, Milan, Italy; Jozef Stefan Institute, Ljubljana, Slovenia; Jozef Stefan International Postgraduate School, Ljubljana, Slovenia; Institut Ruder Boskovic, Zagreb, Croatia; Dipartimento di Energia, Politecnico di Milano, Italy.

This work reports on the investigation of Eurofer-97 erosion behaviour when exposed to the deuterium plasma of the linear device GyM. The erosion dependence of Eurofer-97 on the deuterium ion fluence, 1025 m-2, and temperature of the samples, T = 600 K and 990 K, was addressed. A bias voltage of -200 V was applied to GyM sample holder during the experiments. Samples were deeply characterised by: profilometry, scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, time-of-flight secondary ion mass spectrometry, Rutherford backscattering spectroscopy and particle-induced X-ray emission. The behaviour of Eurofer-97 erosion rate with the ion fluence strictly depends upon temperature. At 600 K, it was 0.14 nm/s after 4.7 × 1024 m-2, then decreased, reaching a steady state value of 0.01 nm/s from 8.0 × 1024 m-2. At 990 K instead, the erosion rate was roughly constant around 0.019 nm/s for 1025 m-2. The value at 2.35 × 1025 m-2 was slightly lower. The erosion rate at 990 K was greater than that at 600 K for every ion fluence. Microscopy and surface analysis techniques showed that Eurofer-97 erosion rate dependence on at 600 K was primarily determined by the preferential sputtering of iron and other mid-Z elements of the alloy, leading to a surface rich in W and Ta difficult to be sputtered. The erosion behaviour at 990 K was dominated by the morphology dynamics, instead. The different properties of the morphology developed at the two temperatures can explain the higher erosion rate at 990 K for all the ion fluences.

Nuclear materials and energy 35 , pp. 101422-1–101422-13

Keywords

plasma facing components, Eurofer-97 steel, erosion, GyM, tokamak

CNR authors

Dellasega David, Ghezzi Francesco Mauro, Mellera Vittoria Antonia, Ricci Daria, Uccello Andrea, Pedroni Matteo

CNR institutes

ISTP – Istituto per la Scienza e Tecnologia dei Plasmi