Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode

Journal Article · Wed Jan 01 00:00:00 EST 2014 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4885346· OSTI ID:1154869

Pigarov, A. Yu. ^[1]; Krasheninnikov, S. I. ^[2]; Rognlien, T. D. ^[3]; Hollmann, E. M. ^[1]; Lasnier, C. J. ^[3]; Unterberg, Ezekial A ^[4]

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1. University of California, San Diego
2. University of California, La Jolla
3. Lawrence Livermore National Laboratory (LLNL)
4. ORNL

Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1154869
• Journal Information: Physics of Plasmas, Vol. 21, Issue 6; ISSN 1070--664X
• Country of Publication: United States
• Language: English