Deuterium release from deuterium plasma-exposed neutron-irradiated and non-neutron-irradiated tungsten samples during annealing

• Published in: Nuclear fusion Vol. 60; no. 9; pp. 96025 - 96033
• Main Authors: Alimov, V.Kh, Hatano, Y., Kuwabara, T., Toyama, T., Someya, Y., Spitsyn, A.V.
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.09.2020
• Subjects: deuterium release under annealing; deuterium retention; neutron-induced defects; tungsten
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/1741-4326/aba337

We examine the effect of neutron irradiation on the release of deuterium from tungsten at 573 K to understand the efficiency of tritium removal by baking out at moderate temperatures. Tungsten samples, undamaged and neutron-irradiated to a damage level of approximately 0.016 displacements per atom, are exposed to low-energy (108 eV), high-flux (3.0 × 1021 to 9.4 × 1021 m−2 s−1) deuterium plasma at temperatures ranging from 573 to 773 K to an ion fluence of 1.1 × 1025 m−2. At each exposure temperature, two undamaged and two neutron-irradiated tungsten samples are exposed to plasma. The deuterium content in the tungsten samples is measured by thermal desorption spectrometry soon after the plasma exposure and after post-plasma annealing at 573 K for 30 h. It is found that: (i) the deuterium retention in the neutron-irradiated tungsten samples is significantly higher than that in the undamaged tungsten samples; (ii) annealing at 573 K of undamaged tungsten samples pre-exposed to deuterium plasma at 573-773 K leads to an almost complete (60%-99%) release of deuterium from the samples; (iii) annealing at 573 K of neutron-irradiated tungsten samples pre-exposed to deuterium plasma at 573-773 K leads to a significant (8%-20%) release of deuterium from the samples.