Abstract
Tungsten targets were first irradiated with high energy W6+ ions (20 MeV) with different dose rates at 800 K and then loaded with deuterium at room temperature to decorate the displacement damage created in the first step. Detailed microstructure investigations were performed and compared with calculated damage profiles and deuterium depth profiles to link defect characteristics with the ability to retain hydrogen isotopes. Results directly indicate that depending on the used dose rate dislocation density and characteristics change. However, deuterium retention does not. Thus, we conclude that overall dislocation density does not affect deuterium retention significantly. Changes in D retention were observed as function of the depth of the damaged zone. Variations of dislocation density were also depth dependent. Consequently, we link changes in D retention with the dislocation presence, number of implanted tungsten ions and other point defects. The latter seem to affects D retention the most.
Highlights
Tungsten is selected as one of the most prominent candidates for plasma facing components in future fusion devices
Tungsten targets were first irradiated with high energy W6+ ions (20MeV) with different dose rates at 800 K and loaded with deuterium at room temperature to decorate the displacement damage created in the first step
Our work shows that dislocation networks in tungsten samples prepared by selfimplantation with different damage dose rate vary with the applied dose rate and depth of W ions penetration
Summary
Tungsten is selected as one of the most prominent candidates for plasma facing components in future fusion devices. It combines satisfactory thermal stability with limited ability to store hydrogen isotopes. Fast neutrons generate a variety of defects in materials exposed to the severe fusion environment [1]. Since neutron sources are not widely available, those available do not offer the right energy spectrum, and samples treated this way exhibit radioactivity, other approaches to simulate displacement damage must be developed. One of them is to irradiate tungsten with high energy tungsten ions to induce defects similar to the ones produced by neutron bombardment [2,3]. Some of the conclusions from these experiments were confirmed with microstructural TEM imaging like insitu radiation experiments [5] or post-mortem observations performed on irradiated specimens [6]
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