The Experts below are selected from a list of 10659 Experts worldwide ranked by ideXlab platform

H. Maier - One of the best experts on this subject based on the ideXlab platform.

D G Whyte - One of the best experts on this subject based on the ideXlab platform.

Yong-seog Kim - One of the best experts on this subject based on the ideXlab platform.

  • kinetics of au containing ternary intermetallic Redeposition at solder ubm interface
    Journal of Electronic Materials, 2001
    Co-Authors: Jong-hyun Lee, Jong-hwan Park, Dong Hyuk Shin, Yong-ho Lee, Yong-seog Kim
    Abstract:

    In this study, the effects of the under bump metallurgy (UBM) structure and Cu content in solders on the Redeposition rate of Au-containing ternary intermetallics at the solder/UBM interface were investigated. A UBM structure with a Ni diffusion barrier, Au/Ni/Cu, appeared to promote the Redeposition of ternary Au-containing intermetallics at the solder/UBM interface of the ternary during the solid-state aging treatment and the Au-embrittlement of the solder interconnections. Copper added to the eutectic Sn-Pb and Sn-Ag solders was observed to be very effective in retarding the Redeposition by forming the ternary intermetallics in solder matrices and preventing the Au-embrittlement. These phenomena were discussed with the microstructures observed.

  • Kinetics of Au-containing ternary intermetallic Redeposition at solder/UBM interface
    Journal of Electronic Materials, 2001
    Co-Authors: Jong-hyun Lee, Jong-hwan Park, Dong Hyuk Shin, Yong-ho Lee, Yong-seog Kim
    Abstract:

    In this study, the effects of the under bump metallurgy (UBM) structure and Cu content in solders on the Redeposition rate of Au-containing ternary intermetallics at the solder/UBM interface were investigated. A UBM structure with a Ni diffusion barrier, Au/Ni/Cu, appeared to promote the Redeposition of ternary Au-containing intermetallics at the solder/UBM interface of the ternary during the solid-state aging treatment and the Au-embrittlement of the solder interconnections. Copper added to the eutectic Sn-Pb and Sn-Ag solders was observed to be very effective in retarding the Redeposition by forming the ternary intermetallics in solder matrices and preventing the Au-embrittlement. These phenomena were discussed with the microstructures observed.

Kaoru Ohya - One of the best experts on this subject based on the ideXlab platform.

  • Redeposition Characteristics of Heavy Hydrocarbon Molecules on a Divertor Plate
    Plasma and Fusion Research, 2011
    Co-Authors: Hayato Kawazome, Kaoru Ohya, Jun Kawata
    Abstract:

    In this study, local Redeposition characteristics of hydrocarbon molecules from the ethane family are investigated using Monte Carlo simulation. Information about Redeposition characteristics is required to estimate tritium retention via Redeposition with chemically eroded hydrocarbon molecules. For the condition of multiple reflections at divertor surface and a plasma density of 1.0 ×10 19 m −3 , the local Redeposition characteristics for injection of ethane family (C2H2 ,C 2H4 ,C 2H6) have been investigated for plasma temperatures ranging from 1 to 100eV. The number of redeposited hydrocarbon molecules increases with plasma temperature because of the increase in impinging particle energy. The increase in sheath potential results in the increase in particle energy. For plasma temperatures lower than 5eV, there is a sudden increase in the number of redeposited particles with plasma temperature because of the increase in the number of impinging molecular ions. Sheath field acceleration is the main mechanism that causes the ions to move to the divertor plate, and the exponential increase in the number of redeposited particles results from the increase in hydrocarbon break-up products in the sheath potential region.

  • Hydrocarbon Redeposition on plasma facing walls intersecting magnetic field at shallow angles
    Japanese Journal of Applied Physics, 2010
    Co-Authors: Kaoru Ohya, K. Inai
    Abstract:

    In present nuclear fusion devices, hydrocarbons resulting from the chemical sputtering of carbon-based walls redeposit on other areas of the wall after transport in plasmas, forming hydrogen-rich carbon layers. A particle-in-cell calculation of a sheath region between the plasma and the wall is incorporated into the transport simulation of methane (CH4) and the fragments in the plasma. The effect of the magnetic field intersecting the wall surface at shallow angles on the Redeposition characteristics is studied, taking the reflection and sticking on the wall into account. The Redeposition rate is rather slowly increased with increasing angle between the magnetic field line and the surface normal, whereas it strongly depends on the plasma temperature and the sticking probability, S, of hydrocarbons (CHx) returning to the surface. By assuming S = 1, the Redeposition of large molecular ions (CH3+ and CH4+) is suppressed at shallow angles (θ> 85°), whereas the Redeposition of atomic C ions is enhanced. For zero sticking (S = 0), the Redeposition is dominated by C ions at high temperature, whereas at low temperature, it is dominated by neutral C atoms.

  • simulation of Redeposition of carbon hydrocarbon on a material surface with castellated structures
    Journal of Nuclear Materials, 2009
    Co-Authors: K. Inai, Kaoru Ohya, Y. Tomita, A. Kirschner, Andrey Litnovsky, T. Tanabe
    Abstract:

    Castellated armor tiles are anticipated to withstand intense heat fluxes on the plasma-facing divertors and limiters. We performed a simulation of the transport and the Redeposition of carbon and hydrocarbons on the castellated structure in order to study the mechanisms of Redeposition in the gaps using realistic plasma penetration in the gap and their energy- and species-dependent reflection on the surface. The calculated profile for the chemical sputtering, but not the physical sputtering, reproduces the experimental deposition profile within an ITER-like castellation geometry in TEXTOR. From the simulation, we proposed a new castellation geometry. The optimization of the shape of the castellated unit cell is very likely to work to minimize the Redeposition rate in the gaps.

  • Simulation of Redeposition of carbon/hydrocarbon on a material surface with castellated structures
    Journal of Nuclear Materials, 2009
    Co-Authors: K. Inai, Kaoru Ohya, Y. Tomita, A. Kirschner, Andrey Litnovsky, T. Tanabe
    Abstract:

    Castellated armor tiles are anticipated to withstand intense heat fluxes on the plasma-facing divertors and limiters. We performed a simulation of the transport and the Redeposition of carbon and hydrocarbons on the castellated structure in order to study the mechanisms of Redeposition in the gaps using realistic plasma penetration in the gap and their energy- and species-dependent reflection on the surface. The calculated profile for the chemical sputtering, but not the physical sputtering, reproduces the experimental deposition profile within an ITER-like castellation geometry in TEXTOR. From the simulation, we proposed a new castellation geometry. The optimization of the shape of the castellated unit cell is very likely to work to minimize the Redeposition rate in the gaps.

  • Transport of Heavy Hydrocarbon and Its Redeposition on Plasma Facing Walls
    2009
    Co-Authors: Kaoru Ohya, Jun Kawata, K. Inai, Hayato Kawazome, Yasuyuki Kikuhara, Tomohide Nakano, Yoshio Ueda, Tetsuo Tanabe
    Abstract:

    Redeposition of C2H4 and C2H6 chemically eroded from carbon walls is simulated by EDDY code incorporated by the reflection on a hydrogenated and amorphized carbon surface. The Redeposition rate for heavy hydrocarbons is drastically decreased by introduction of the reflection. The Redeposition patterns on the surface are enlarged by the reflection, but it is narrower for the heavy hydrocarbons than for CH4. The photon emissions of C2 from C2H4 (C2H6) decay faster than that of CH from CH4 in high-temperature (>10 eV) plasmas, which reproduces the difference of the decay of the CD and C2 light intensities observed in the vicinity of the outer diverter plates of JT-60U. For such temperatures, the calculated inverse photon-efficiency D/XB is in good agreement with the observed values, whereas it decreases faster with deceasing temperature up to 5 eV and then increases with a further decrease of temperature.

J. P. Coad - One of the best experts on this subject based on the ideXlab platform.

  • similarities in divertor erosion Redeposition and deuterium retention patterns between the tokamaks asdex upgrade diii d and jet
    Nuclear Fusion, 1999
    Co-Authors: D G Whyte, J. P. Coad, P. Franzen, H. Maier
    Abstract:

    The similar poloidal patterns of divertor erosion and Redeposition of the ASDEX Upgrade, DIII-D and JET tokamaks are examined by comparing hydrogen isotope retention at the surfaces of divertor tiles. The outer divertor strike point undergoes net erosion. The inner divertor is a region of net Redeposition, with deuterium co-deposition rates ~20 μg m2 s-1 for all three devices; despite their differences in geometry, size and plasma facing materials. This extrapolates to an unacceptably high tritium retention rate in a DT burning steady state tokamak.

  • Similarities in divertor erosion/Redeposition and deuterium retention patterns between the tokamaks ASDEX Upgrade, DIII-D and JET
    Nuclear Fusion, 1999
    Co-Authors: Dennis Whyte, J. P. Coad, P. Franzen, H. Maier
    Abstract:

    The similar poloidal patterns of divertor erosion and Redeposition of the ASDEX Upgrade, DIII-D and JET tokamaks are examined by comparing hydrogen isotope retention at the surfaces of divertor tiles. The outer divertor strike point undergoes net erosion. The inner divertor is a region of net Redeposition, with deuterium co-deposition rates ~20 μg m2 s-1 for all three devices; despite their differences in geometry, size and plasma facing materials. This extrapolates to an unacceptably high tritium retention rate in a DT burning steady state tokamak.

  • Redeposition effects on the target plates of the JET tokamak
    Vacuum, 1994
    Co-Authors: J. P. Coad, B Farmery
    Abstract:

    Abstract Complete tiles from the X-point target region of the JET tokamak can be analysed by ion beam techniques in a special chamber equipped to handle beryllium- and tritium-contaminated samples. From the amounts of deuterium co-deposited during plasma operations, and the pattern of beryllium deposits remaining from regular Be evaporation in the torus, erosion and Redeposition effects at the target area can be determined. The largest amounts of net Redeposition occur in the ‘private zone’ and near the inner separatrix. There appears to be a net transfer of material from the outer to the inner strike zone: the data are compared with models for divertor transport.