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Your search keyword '"Tynan, G.R."' showing total 17 results
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17 results on '"Tynan, G.R."'

9. Deuterium supersaturated surface layer in tungsten: ion energy dependence.

Author

Nishijima, D., Tokitani, M., Nagata, D., Schwarz-Selinger, T., Založnik, A., Chang, F., Doerner, R.P., Patino, M.I., Simmonds, M.J., Baldwin, M.J., and Tynan, G.R.

Subjects
ION energy, LASER-induced breakdown spectroscopy, TUNGSTEN, NUCLEAR reactions, LASER plasmas, TRANSMISSION electron microscopy, DEUTERIUM, PLASMA devices
Abstract

Properties of deuterium (D) supersaturated surface layers (DSSLs) formed in tungsten (W), such as thickness, internal microstructures, and D retention, are experimentally investigated as a function of the incident ion energy, E i. W samples were exposed to D plasmas in the PISCES-A linear plasma device in a range of E i ∼ 45–175 eV, while other plasma exposure parameters were fixed: sample temperature, T s, ∼423 K, ion flux, Γi, ∼1.2 × 1021 m−2s−1, and fluence, Φi, ∼3.0 × 1024 m−2. High-resolution, cross-sectional, transmission electron microscopy observations confirm that (1) a DSSL forms even at the lowest E i ∼ 45 eV, (2) the DSSL thickness, Δ t DSSL, is found to decrease with decreasing E i from ∼11–12 nm at E i ∼ 175 eV to ∼5–6 nm at ∼45 eV, and to agree with approximately the maximum implantation depth calculated using SDTrimSP, and (3) high-density D nanobubbles with a diameter of ∼1 nm or less exist inside the DSSL, which is deemed to validate a theory-predicted vacancy stabilization process due to trapping of a solute D atom(s). Utilizing a D areal density of ∼4.2 × 1019 m−2 in the first 14 nm from the surface at E i ∼ 75 eV from nuclear reaction analysis and the measured E i dependence of Δ t DSSL, our previous laser-induced breakdown spectroscopy data is updated: both dynamic and static D retention increase with decreasing E i, and the D/W atomic fraction during plasma exposure reaches ∼0.3 at E i ∼ 45 eV. A possible DSSL formation mechanism is proposed. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Direct observations of L-I-H and H-I-L transitions with the X-point reciprocating probe in ASDEX Upgrade

Author

Mueller, S.H., Conway, G.D., Birkenmeier, G., Carralero, D., Happel, T., Herrmann, A., Manz, P., de Marne, P., Mlynek, A., Müller, H.W., Potzel, S., Rohde, V., Stroth, U., Tsalas, M., Tynan, G.R., Wolfrum, E., Team, ASDEXUpgrade, and ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Physics, symbols.namesake, Toroid, ASDEX Upgrade, Mach number, Turbulence, Divertor, Phase (waves), symbols, Electron temperature, Langmuir probe, Atomic physics, Condensed Matter Physics
Abstract

A reciprocating Langmuir probe was used to directly measure the behavior of turbulence and flows in the X-point region during transitions between low-(L) and high-confinement (H) mode in ASDEX Upgrade. The probe traverses the divertor horizontally in 140 ms, typically 2–5 cm below the X-point. Toroidal Mach number, density, floating potential (ϕf), and electron temperature (Te) are measured. In the regime accessible to the probe (Pinj

Published
2014

17. Fusion materials science and technology research opportunities now and during the ITER era

Author

Zinkle, S.J., primary, Blanchard, J.P., additional, Callis, R.W., additional, Kessel, C.E., additional, Kurtz, R.J., additional, Lee, P.J., additional, McCarthy, K.A., additional, Morley, N.B., additional, Najmabadi, F., additional, Nygren, R.E., additional, Tynan, G.R., additional, Whyte, D.G., additional, Willms, R.S., additional, and Wirth, B.D., additional

Published
2014
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