Numerical simulations of blobs with ion dynamics

Anders Henry Nielsen, Jens Juul Rasmussen, Jens Madsen, G. S. Xu, Volker Naulin, Jeppe Miki Busk Olsen, Michael Løiten Magnussen, S.K. Hansen, Ning Yan, Laust Emil Hjerrild Tophøj, B. N. Wan

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Abstract

The transport of particles and energy into the scrape-off layer (SOL) region at the outboard midplane of medium-sized tokamaks, operating in low confinement mode, is investigated by applying the first-principle HESEL (hot edge-sol-electrostatic) model. HESEL is a four-field drift-fluid model including finite electron and ion temperature effects, drift wave dynamics on closed field lines, and sheath dynamics on open field lines. Particles and energy are mainly transported by intermittent blobs. Therefore, blobs have a significant influence on the corresponding profiles. The formation of a 'shoulder' in the SOL density profile can be obtained by increasing the collisionality or connection length, thus decreasing the efficiency of the SOL's ability to remove plasma. As the ion pressure has a larger perpendicular but smaller parallel dissipation rate compared to the electron pressure, ion energy is transported far into the SOL. This implies that the ion temperature in the SOL exceeds the electron temperature by. a factor of 2-4 and significantly broadens the power deposition profile.
Original languageEnglish
Article number025012
JournalPlasma Physics and Controlled Fusion
Volume59
Issue number2
Number of pages12
ISSN0741-3335
DOIs
Publication statusPublished - 2017

Keywords

  • Blob dynamics
  • Scrape-off layer transport
  • Turbulence and flows
  • Simulations

Cite this

Nielsen, A. H., Rasmussen, J. J., Madsen, J., Xu, G. S., Naulin, V., Olsen, J. M. B., Magnussen, M. L., Hansen, S. K., Yan, N., Tophøj, L. E. H., & Wan, B. N. (2017). Numerical simulations of blobs with ion dynamics. Plasma Physics and Controlled Fusion, 59(2), [025012]. https://doi.org/10.1088/1361-6587/59/2/025012