Hydrogen-vacancy interaction in W and Mo

Keriem, M.S. Abd El; Werf, D. P. van der; Pleiter, F.

doi:10.1007/bf00567608

Cited by 2 publications

(2 citation statements)

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“…This value is in line with the literature, which quotes values ranging from 1.0-1.4 eV [46,47,48,49,50]. If the trap energy were closer to 1.4 eV, this would result in lower saturation levels in the model than if the trap energy was assumed to be 1.55 eV.…”

Section: Thermal Desorptionsupporting

confidence: 90%

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Dynamics of Plasma-Surface Interactions using In-situ Ion Beam Analysis

Whyte¹

2009

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SummaryThe overall goal of this proposal was to develop an innovative experimental facility that would allow for the measurement of real-time response of a material surface to plasma bombardment by employing in-situ high-energy ion beam analysis. This facility was successfully developed and deployed at U. Wisconsin-Madison and was named DIONISOS (Dynamics of IONic Implantation & Sputtering on Surfaces).There were several major highlights to the DIONISOS research which we will briefly highlight below. The full technical details of the DIONISOS development, deployment and research results are contained in the Appendices which contain several peer-reviewed publications and a PhD thesis devoted to DIONISOS. The DIONISOS results on deuterium retention in molybdenum were chosen as an invited talk at the 2008 International Conference on Plasma-Surface Interactions in Toledo, Spain. Design HighlightsThe DIONISOS design activity was significant. For the first time ever, a high power magnetized plasma environment was combine with high-energy ion beams from an accelerator. This posed several unique challenges that were overcome in the first 1.5 years of design and implementation.1. The 1.7 MV tandem ion accelerator was refurbished and commissioned. The accelerator was re-assembled and installed at UW-Madison after being shipped from Bell Labs in New Jersey, from where it was purchased 2. A dedicated plasma exposure chamber was designed which featured several innovations ( Fig. 1 5. Innovative charged-particle detectors for ion beam analysis that included active cooling and particle shielding from the nearby plasma. This allowed in-situ surface analysis when the plasma was bombarding the target samples.6. Remotely controlled beam-steering and rastering across the sample face using upstream electrostatic deflectors and strong differential pumping.7. Plasma diagnostics including a scanning langmuir probe and infrared thermography of the target.In summary, the design was successful at integrating a high flux plasma exposure chamber with real-time in-situ ion beam surface analysis for the first time. Fig. 2 Photos of the DIONISOS target chamber a) Rotatable target assembly with active heating/cooling and electrical biasing. Overlays shows how the ~mm diameter ion beam can be scanned across the plasma profile. B) Deuterium helicon plasma incident on a molybdenum target. Research HighlightsThe latter half of the research grant activity focused on deuterium fuel retention in refractory metals. In future burning plasma devices like ITER, tritium fuel retention is a serious safety concern; and tritium fuel economy is a concern for eventual fusion reactors breeding their own tritium. At the same time, refractory metals such as molybdenum and tungsten are leading candidates as PFC materials because of their erosion resistance. We used the unique scientific measurement tools of DIONISOS to explore the dynamic interaction of a deuterium plasma with the metals to illuminate fundamental process of importance. Further motivation was provid...

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Section: Thermal Desorptionsupporting

confidence: 90%

“…Nagata et al implanted a thin Several studies have been made to determine the binding energies of hydrogen atoms in vacancies, thought to be the most common trap site in Mo, using a variety of techniques including TDS [46,47,48,49,50]. Typical trap energies ranged from 1.0-1.4 eV.…”

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Dynamics of Plasma-Surface Interactions using In-situ Ion Beam Analysis

Whyte¹

2009

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Dynamic Simulation of Multiplier Effects of Helium Plasma and Neutron Irradiation on Microstructural Evolution in Tungsten

Yoshida

Yoshiie

2005

Mater. Trans.

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Plasma-facing and high heat flux materials in a fusion reactor suffer two types of damage: displacement damage caused mainly by highenergy neutrons and surface damage, such as erosion, sputtering, and blistering, caused by hydrogen and helium plasma. Usually, these two kinds of damage are investigated separately. In the present study, multiplier effects of helium plasma and neutron irradiation on microstructural evolution in tungsten were investigated using computer simulations based on a rate theory. Neutron irradiation with 10 À6 dpaÁs À1 at 873 K and a helium flux of 10 18 m À2 Ás À1 with 10-keV energy were used as typical irradiation conditions. The effects of irradiation temperature and defect production rate on the interaction between helium and defects were also investigated. The simulation results revealed the rapid diffusion of helium in tungsten. The helium concentration was saturated in tungsten 0.067 mm thick within 0.01 s at 873 K, and the formation of heliumvacancy clusters was nearly uniform in the matrix except at the surfaces facing towards and away from the irradiation after 0.01 s. This meant that the 10-keV helium plasma could enhance formation of helium-vacancy clusters in the region without damage produced by helium. The concentration of 6He-V clusters reached a very high level (10 À6 ) even after a 1-s irradiation with a defect production rate of 10 À6 dpaÁs À1 at 873 K. The concentration of helium-vacancy clusters decreased with increasing irradiation temperature and decreasing defect production rate. The accumulation of helium and the formation of helium-vacancy clusters depended on not only the vacancy concentration, which was determined by the irradiation temperature and defect production rate, and helium concentrations, but also irradiation time.

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Hydrogen-vacancy interaction in W and Mo

Cited by 2 publications

References 9 publications

Dynamics of Plasma-Surface Interactions using In-situ Ion Beam Analysis

Dynamics of Plasma-Surface Interactions using In-situ Ion Beam Analysis

Dynamic Simulation of Multiplier Effects of Helium Plasma and Neutron Irradiation on Microstructural Evolution in Tungsten

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