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Title: Comparison of fluid neutral models for one-dimensional plasma edge modeling with a finite volume solution of the Boltzmann equation

We derive fluid neutral approximations for a simplified 1D edge plasma model, suitable to study the neutral behavior close to the target of a nuclear fusion divertor, and compare its solutions to the solution of the corresponding kinetic Boltzmann equation. The plasma is considered as a fixed background extracted from a detached 2D simulation. We show that the Maxwellian equilibrium distribution is already obtained very close to the target, justifying the use of a fluid approximation. We compare three fluid neutral models: (i) a diffusion model; (ii) a pressure-diffusion model (i.e., a combination of a continuity and momentum equation) assuming equal neutral and ion temperatures; and (iii) the pressure-diffusion model coupled to a neutral energy equation taking into account temperature differences between neutrals and ions. Partial reflection of neutrals reaching the boundaries is included in both the kinetic and fluid models. We propose two methods to obtain an incident neutral flux boundary condition for the fluid models: one based on a diffusion approximation and the other assuming a truncated Chapman-Enskog distribution. The pressure-diffusion model predicts the plasma sources very well. The diffusion boundary condition gives slightly better results overall. Although including an energy equation still improves the results, the assumptionmore » of equal ion and neutral temperature already gives a very good approximation.« less
Authors:
;  [1] ;  [2] ;  [3]
  1. KU Leuven, Department of Mechanical Engineering, Celestijnenlaan 300A, 3001 Leuven (Belgium)
  2. ITER Organization, route de Vinon-sur-Verdon, 13067 St. Paul lez Durance Cedex (France)
  3. KU Leuven, Department of Computer Science, Celestijnenlaan 200A, 3001 Leuven (Belgium)
Publication Date:
OSTI Identifier:
22493819
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 1; Other Information: (c) 2016 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; APPROXIMATIONS; BOLTZMANN EQUATION; BOLTZMANN STATISTICS; BOUNDARY CONDITIONS; DIVERTORS; EDGE LOCALIZED MODES; EQUILIBRIUM; MATHEMATICAL SOLUTIONS; ONE-DIMENSIONAL CALCULATIONS; PLASMA FLUID EQUATIONS; REFLECTION; TWO-DIMENSIONAL CALCULATIONS