The effect of carbon impurities on molybdenum surface morphology evolution under high-flux low-energy helium ion irradiation

JOURNAL OF NUCLEAR MATERIALS

卷:478

Article

Tripathi, J. K.¹  Novakowski, T. J.¹  Gonderman, S.¹  Bharadwaj, N.¹  Hassanein, A.¹ 

[1] Purdue Univ, Sch Nucl Engn, Ctr Mat Extreme Environm CMUXE, W Lafayette, IN 47907 USA

关键词: Plasma-facing materials;    Molybdenum;    Fuzz formation;    Ion irradiation;    Atomic force microscopy;    X-ray photoelectron spectroscopy;    Optical reflectivity;   

DOI  :  10.1016/j.jnucmat.2016.06.026

来源: Elsevier

【 摘 要 】

We report on the role of carbon (C) impurities, in molybdenum (Mo) fuzz evolutions on Mo surface during 100 eV He+ ion irradiations. In this study we considered 0.01, 0.05, and 0.5% C+ ion impurities in He+ ion irradiations. For introducing such tiny C+ ion impurities, gas mixtures of He and CH4 have been chosen in following ratios; 99.95: 0.05, 99.75: 0.25, and 97.5: 2.5. Apart from these three cases, two additional cases, 100% He+ ion (for Mo fuzz growth due to only He+ ions) and 100% H+ ion (for confirming the significance of tiny 0.04-2.0% H+ ions in terms of Mo fuzz evolutions on Mo surface, if any), have also been considered. Ion energy (100 eV), ion fluence (2.6 x 10(24) ions m(-2)), and target temperature (923 K) were kept constant for each experiment and their selections were based on our previous studies [1,2]. Our study shows homogeneously populated and highly dense Mo fuzz evolutions on entire Mo surface for 100% He+ ion irradiation case. Enhancement of C+ ion impurities in He+ ions causes a sequential reduction in Mo fuzz evolutions, leading to almost complete prevention of Mo fuzz evolutions for 0.5% C+ ion impurity concentrations. Additionally, no fuzz formation for 100% H+ ion irradiation at all, were seen (apart from some tiny nano- structuring, in very limited regions). This indicates that there is no significant role of H+ ions in Mo fuzz evolutions (at least for such tiny amount, 0.04-2.0% H+ ions). The study is significant to understand the behavior of potential high- Z plasma facing components (PFCs), in the, presence of tiny amount of C impurities, for nuclear fusion relevant applications. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

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