The Experts below are selected from a list of 33 Experts worldwide ranked by ideXlab platform
M.e. Rensink - One of the best experts on this subject based on the ideXlab platform.
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Edge plasma modeling of limiter surfaces in a Tokamak divertor Configuration
Journal of Nuclear Materials, 1999Co-Authors: M.e. Rensink, T.d. RognlienAbstract:We describe a 2-D model for edge plasmas with localized limiter surfaces penetrating the scrape-off layer. The model is used to simulate an idealized ITER Startup Configuration with variations in the limiter penetration depth and surface shape. The results show that the distribution of the total heat load between divertor plates and outer midplane limiter surfaces can be controlled by the penetration depth of the limiter. The limiter surface can be shaped to reduce the peak heat flux without significantly changing the total heat loads. The tentative conclusion is that ITER Startup on an outer midplane limiter is reasonable because the total and peak heat loads can be controlled by the limiter positioning and shape.
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Edge plasma modeling of limiter surfaces in a Tokamak divertor Configuration
1998Co-Authors: M.e. RensinkAbstract:During the Startup phase of a tokamak the plasma Configuration may evolve from a limiter to a divertor Configuration. Some of the particle and heat flux from the core will be deposited on material surfaces near the separatrix instead of the divertor plates. Examples of such surfaces include the center-post in most tokamaks, baffles near the x-point that create closed divertors, and outboard limiter surfaces. Two-dimensional edge plasma models for tokamak divertor Configurations typically give detailed information about the particle and heat fluxes on the divertor plates, but yield little or no information about fluxes on these other localized surfaces near the core plasma. To realistically model the Startup phase of a tokamak it is necessary to compute the plasma interaction with both limiter and divertor surfaces. The UEDGE code [l] has been modified to include these limiter surfaces. In this report we present simulation results for an idealized ITER [2] Startup Configuration with variations in the limiter penetration depth and surface shape.
Detlev Reiter - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation of plasma edge transport and limiter heat fluxes in Wendelstein 7-X Startup plasmas with EMC3-EIRENE
Nuclear Fusion, 2017Co-Authors: F. Effenberg, Y. Feng, H. Frerichs, Oliver Schmitz, Sergey Bozhenkov, H. Hölbe, R. König, M. Krychowiak, T. Sunn Pedersen, Detlev ReiterAbstract:The results of a first systematic assessment of plasma edge transport processes for the limiter Startup Configuration at Wendelstein 7-X are presented. This includes an investigation of transport from intrinsic and externally injected impurities and their impact on the power balance and limiter heat fluxes. The fully 3D coupled plasma fluid and kinetic neutral transport Monte Carlo code EMC3-EIRENE is used. The analysis of the magnetic topology shows that the poloidally and toroidally localized limiters cause a 3D helical scrape-off layer (SOL) consisting of magnetic flux tubes of three different connection lengths L C. The transport in the helical SOL is governed by L C as topological scale length for the parallel plasma loss channel to the limiters. A clear modulation of the plasma pressure with L C is seen. The helical flux tube topology results in counter streaming sonic plasma flows. The heterogeneous SOL plasma structure yields an uneven limiter heat load distribution with localized peaking. Assuming spatially constant anomalous transport coefficients, increasing plasma density yields a reduction of the maximum peak heat loads from 12 MWm−2 to 7.5 MWm−2 and a broadening of the deposited heat fluxes. The impact of impurities on the limiter heat loads is studied by assuming intrinsic carbon impurities eroded from the limiter surfaces with a gross chemical sputtering yield of 2. The resulting radiative losses account for less than 10% of the input power in the power balance with marginal impact on the limiter heat loads. It is shown that a significant mitigation of peak heat loads, 40–50%, can be achieved with controlled impurity seeding with nitrogen and neon, which is a method of particular interest for the later island divertor phase.
F. Effenberg - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation of plasma edge transport and limiter heat fluxes in Wendelstein 7-X Startup plasmas with EMC3-EIRENE
Nuclear Fusion, 2017Co-Authors: F. Effenberg, Y. Feng, H. Frerichs, Oliver Schmitz, Sergey Bozhenkov, H. Hölbe, R. König, M. Krychowiak, T. Sunn Pedersen, Detlev ReiterAbstract:The results of a first systematic assessment of plasma edge transport processes for the limiter Startup Configuration at Wendelstein 7-X are presented. This includes an investigation of transport from intrinsic and externally injected impurities and their impact on the power balance and limiter heat fluxes. The fully 3D coupled plasma fluid and kinetic neutral transport Monte Carlo code EMC3-EIRENE is used. The analysis of the magnetic topology shows that the poloidally and toroidally localized limiters cause a 3D helical scrape-off layer (SOL) consisting of magnetic flux tubes of three different connection lengths L C. The transport in the helical SOL is governed by L C as topological scale length for the parallel plasma loss channel to the limiters. A clear modulation of the plasma pressure with L C is seen. The helical flux tube topology results in counter streaming sonic plasma flows. The heterogeneous SOL plasma structure yields an uneven limiter heat load distribution with localized peaking. Assuming spatially constant anomalous transport coefficients, increasing plasma density yields a reduction of the maximum peak heat loads from 12 MWm−2 to 7.5 MWm−2 and a broadening of the deposited heat fluxes. The impact of impurities on the limiter heat loads is studied by assuming intrinsic carbon impurities eroded from the limiter surfaces with a gross chemical sputtering yield of 2. The resulting radiative losses account for less than 10% of the input power in the power balance with marginal impact on the limiter heat loads. It is shown that a significant mitigation of peak heat loads, 40–50%, can be achieved with controlled impurity seeding with nitrogen and neon, which is a method of particular interest for the later island divertor phase.
T.d. Rognlien - One of the best experts on this subject based on the ideXlab platform.
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Edge plasma modeling of limiter surfaces in a Tokamak divertor Configuration
Journal of Nuclear Materials, 1999Co-Authors: M.e. Rensink, T.d. RognlienAbstract:We describe a 2-D model for edge plasmas with localized limiter surfaces penetrating the scrape-off layer. The model is used to simulate an idealized ITER Startup Configuration with variations in the limiter penetration depth and surface shape. The results show that the distribution of the total heat load between divertor plates and outer midplane limiter surfaces can be controlled by the penetration depth of the limiter. The limiter surface can be shaped to reduce the peak heat flux without significantly changing the total heat loads. The tentative conclusion is that ITER Startup on an outer midplane limiter is reasonable because the total and peak heat loads can be controlled by the limiter positioning and shape.
Y. Feng - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation of plasma edge transport and limiter heat fluxes in Wendelstein 7-X Startup plasmas with EMC3-EIRENE
Nuclear Fusion, 2017Co-Authors: F. Effenberg, Y. Feng, H. Frerichs, Oliver Schmitz, Sergey Bozhenkov, H. Hölbe, R. König, M. Krychowiak, T. Sunn Pedersen, Detlev ReiterAbstract:The results of a first systematic assessment of plasma edge transport processes for the limiter Startup Configuration at Wendelstein 7-X are presented. This includes an investigation of transport from intrinsic and externally injected impurities and their impact on the power balance and limiter heat fluxes. The fully 3D coupled plasma fluid and kinetic neutral transport Monte Carlo code EMC3-EIRENE is used. The analysis of the magnetic topology shows that the poloidally and toroidally localized limiters cause a 3D helical scrape-off layer (SOL) consisting of magnetic flux tubes of three different connection lengths L C. The transport in the helical SOL is governed by L C as topological scale length for the parallel plasma loss channel to the limiters. A clear modulation of the plasma pressure with L C is seen. The helical flux tube topology results in counter streaming sonic plasma flows. The heterogeneous SOL plasma structure yields an uneven limiter heat load distribution with localized peaking. Assuming spatially constant anomalous transport coefficients, increasing plasma density yields a reduction of the maximum peak heat loads from 12 MWm−2 to 7.5 MWm−2 and a broadening of the deposited heat fluxes. The impact of impurities on the limiter heat loads is studied by assuming intrinsic carbon impurities eroded from the limiter surfaces with a gross chemical sputtering yield of 2. The resulting radiative losses account for less than 10% of the input power in the power balance with marginal impact on the limiter heat loads. It is shown that a significant mitigation of peak heat loads, 40–50%, can be achieved with controlled impurity seeding with nitrogen and neon, which is a method of particular interest for the later island divertor phase.