Super-saturated hydrogen effects on radiation damages in tungsten under the high-flux divertor plasma irradiation. (14th July 2015)

• Record Type: Journal Article
• Authors: Kato, D.; Iwakiri, H.; Watanabe, Y.; Morishita, K.; Muroga, T.
• Is Part Of: Nuclear fusion. Volume 55:Number 8(2015:Aug.)
• Publication Date: 2015-07-14
• Subjects: tungsten divertor -- radiation damage -- density functional theory; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/0029-5515/55/8/083019
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: Tungsten is a prime candidate as the divertor material of the ITER and DEMO reactors, which would be exposed to unprecedentedly high-flux plasmas as well as neutrons. For a better characterization of radiation damages in the tungsten under the divertor condition, we examine influences of super-saturated hydrogen on vacancies in the tungsten. The present calculations based on density functional theory (DFT) reveal unusual phenomena predicted at a super-saturated hydrogen concentration: (1) strongly enhanced vacancy concentration with the super-saturated hydrogen concentration is predicted by a thermodynamics model assuming multiple-hydrogen trapping, i.e. hydrogen clusters formation, in the vacancies; and (2) DFT molecular dynamics revealed that hydrogen clusters can prevent a vacancy from recombining with the neighboring crowdion-type self-interstitial-atom. This suggests that neutron damage effects will be increased in the presence of the hydrogen clusters.