On coupling fluid plasma and kinetic neutral physics models

The coupled fluid plasma and kinetic neutral physics equations are analyzed through theory and simulation of benchmark cases. It is shown that coupling methods that do not treat the coupling rates implicitly are restricted to short time steps for stability. Fast charge exchange, ionization and recom...

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Main Authors: I. Joseph, M.E. Rensink, D.P. Stotler, A.M. Dimits, L.L. LoDestro, G.D. Porter, T.D. Rognlien, B. Sjogreen, M.V. Umansky
Format: Article
Language:English
Published: Elsevier 2017-08-01
Series:Nuclear Materials and Energy
Online Access:http://www.sciencedirect.com/science/article/pii/S2352179116302149
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spelling doaj-8caab6611ca94786ad72fad0f08019222020-11-25T00:09:56ZengElsevierNuclear Materials and Energy2352-17912017-08-0112813818On coupling fluid plasma and kinetic neutral physics modelsI. Joseph0M.E. Rensink1D.P. Stotler2A.M. Dimits3L.L. LoDestro4G.D. Porter5T.D. Rognlien6B. Sjogreen7M.V. Umansky8Corresponding author.; Lawrence Livermore National Laboratory, Livermore CA 94551, USALawrence Livermore National Laboratory, Livermore CA 94551, USAPrinceton Plasma Physics Laboratory, Princeton, NJ, USALawrence Livermore National Laboratory, Livermore CA 94551, USALawrence Livermore National Laboratory, Livermore CA 94551, USALawrence Livermore National Laboratory, Livermore CA 94551, USALawrence Livermore National Laboratory, Livermore CA 94551, USALawrence Livermore National Laboratory, Livermore CA 94551, USALawrence Livermore National Laboratory, Livermore CA 94551, USAThe coupled fluid plasma and kinetic neutral physics equations are analyzed through theory and simulation of benchmark cases. It is shown that coupling methods that do not treat the coupling rates implicitly are restricted to short time steps for stability. Fast charge exchange, ionization and recombination coupling rates exist, even after constraining the solution by requiring that the neutrals are at equilibrium. For explicit coupling, the present implementation of Monte Carlo correlated sampling techniques does not allow for complete convergence in slab geometry. For the benchmark case, residuals decay with particle number and increase with grid size, indicating that they scale in a manner that is similar to the theoretical prediction for nonlinear bias error. Progress is reported on implementation of a fully implicit Jacobian-free Newton–Krylov coupling scheme. The present block Jacobi preconditioning method is still sensitive to time step and methods that better precondition the coupled system are under investigation. Keywords: Divertor modeling, Charge exchange, Ionization, Recombination, Implicit, Newton–Krylov, UEDGE, DEGAS2, EIRENE, SOLPS, MSC: 00-01, 99-00http://www.sciencedirect.com/science/article/pii/S2352179116302149
collection DOAJ
language English
format Article
sources DOAJ
author I. Joseph
M.E. Rensink
D.P. Stotler
A.M. Dimits
L.L. LoDestro
G.D. Porter
T.D. Rognlien
B. Sjogreen
M.V. Umansky
spellingShingle I. Joseph
M.E. Rensink
D.P. Stotler
A.M. Dimits
L.L. LoDestro
G.D. Porter
T.D. Rognlien
B. Sjogreen
M.V. Umansky
On coupling fluid plasma and kinetic neutral physics models
Nuclear Materials and Energy
author_facet I. Joseph
M.E. Rensink
D.P. Stotler
A.M. Dimits
L.L. LoDestro
G.D. Porter
T.D. Rognlien
B. Sjogreen
M.V. Umansky
author_sort I. Joseph
title On coupling fluid plasma and kinetic neutral physics models
title_short On coupling fluid plasma and kinetic neutral physics models
title_full On coupling fluid plasma and kinetic neutral physics models
title_fullStr On coupling fluid plasma and kinetic neutral physics models
title_full_unstemmed On coupling fluid plasma and kinetic neutral physics models
title_sort on coupling fluid plasma and kinetic neutral physics models
publisher Elsevier
series Nuclear Materials and Energy
issn 2352-1791
publishDate 2017-08-01
description The coupled fluid plasma and kinetic neutral physics equations are analyzed through theory and simulation of benchmark cases. It is shown that coupling methods that do not treat the coupling rates implicitly are restricted to short time steps for stability. Fast charge exchange, ionization and recombination coupling rates exist, even after constraining the solution by requiring that the neutrals are at equilibrium. For explicit coupling, the present implementation of Monte Carlo correlated sampling techniques does not allow for complete convergence in slab geometry. For the benchmark case, residuals decay with particle number and increase with grid size, indicating that they scale in a manner that is similar to the theoretical prediction for nonlinear bias error. Progress is reported on implementation of a fully implicit Jacobian-free Newton–Krylov coupling scheme. The present block Jacobi preconditioning method is still sensitive to time step and methods that better precondition the coupled system are under investigation. Keywords: Divertor modeling, Charge exchange, Ionization, Recombination, Implicit, Newton–Krylov, UEDGE, DEGAS2, EIRENE, SOLPS, MSC: 00-01, 99-00
url http://www.sciencedirect.com/science/article/pii/S2352179116302149
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