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Title: 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 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.
Authors:
; ; ORCiD logo [1] ; ; ; ; ; ;
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-697766
Journal ID: ISSN 2352-1791; PII: S2352179116302149
Grant/Contract Number:
AC52-07NA27344; 15-ERD-059; AC02-09CH11466
Type:
Published Article
Journal Name:
Nuclear Materials and Energy
Additional Journal Information:
Journal Volume: 12; Journal ID: ISSN 2352-1791
Publisher:
Elsevier
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Divertor modeling; Charge exchange; Ionization; Recombination; Implicit; Newton–Krylov; UEDGE; DEGAS2; EIRENE; SOLPS; 74 ATOMIC AND MOLECULAR PHYSICS; 70 PLASMA PHYSICS AND FUSION
OSTI Identifier:
1347040
Alternate Identifier(s):
OSTI ID: 1349230; OSTI ID: 1366930

Joseph, I., Rensink, M. E., Stotler, D. P., Dimits, A. M., LoDestro, L. L., Porter, G. D., Rognlien, T. D., Sjogreen, B., and Umansky, M. V.. On coupling fluid plasma and kinetic neutral physics models. United States: N. p., Web. doi:10.1016/j.nme.2017.02.021.
Joseph, I., Rensink, M. E., Stotler, D. P., Dimits, A. M., LoDestro, L. L., Porter, G. D., Rognlien, T. D., Sjogreen, B., & Umansky, M. V.. On coupling fluid plasma and kinetic neutral physics models. United States. doi:10.1016/j.nme.2017.02.021.
Joseph, I., Rensink, M. E., Stotler, D. P., Dimits, A. M., LoDestro, L. L., Porter, G. D., Rognlien, T. D., Sjogreen, B., and Umansky, M. V.. 2017. "On coupling fluid plasma and kinetic neutral physics models". United States. doi:10.1016/j.nme.2017.02.021.
@article{osti_1347040,
title = {On coupling fluid plasma and kinetic neutral physics models},
author = {Joseph, I. and Rensink, M. E. and Stotler, D. P. and Dimits, A. M. and LoDestro, L. L. and Porter, G. D. and Rognlien, T. D. and Sjogreen, B. and Umansky, M. V.},
abstractNote = {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.},
doi = {10.1016/j.nme.2017.02.021},
journal = {Nuclear Materials and Energy},
number = ,
volume = 12,
place = {United States},
year = {2017},
month = {3}
}