Three-dimensional simulations of plasma turbulence in the RFX-mod scrape-off layer and comparison with experimental measurements

Fabio Riva, Nicola Vianello, Monica Spolaore, Paolo Ricci, Roberto Cavazzana, Lionello Marrelli, Silvia Spagnolo

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Abstract

The tokamak scrape-off layer (SOL) plasma dynamics is investigated in a circular limiter configuration with a low edge safety factor. Focusing on the experimental parameters of two ohmic tokamak inner-wall limited plasma discharges in RFX-mod [Sonato et al., Fusion Eng. Des. 74, 97 (2005)], nonlinear SOL plasma simulations are performed with the GBS code [Ricci et al., Plasma Phys. Controlled Fusion 54, 124047 (2012)]. The numerical results are compared with the experimental measurements, assessing the reliability of the GBS model in describing the RFX-mod SOL plasma dynamics. It is found that the simulations are able to quantitatively reproduce the RFX-mod experimental measurements of the electron plasma density, electron temperature, and ion saturation current density (jsat) equilibrium profiles. Moreover, there are indications that the turbulent transport is driven by the same instability in the simulations and in the experiment, with coherent structures having similar statistical properties. On the other hand, it is found that the simulation results are not able to correctly reproduce the floating potential equilibrium profile and the jsatfluctuation level. It is likely that these discrepancies are, at least in part, related to simulating only the tokamak SOL region, without including the plasma dynamics inside the last close flux surface, and to the limits of applicability of the drift approximation. The turbulence drive is then identified from the nonlinear simulations and with the linear theory. It results that the inertial drift wave is the instability driving most of the turbulent transport in the considered discharges.
Original languageEnglish
Article number022305
Pages (from-to)-
JournalPhysics of Plasmas
Volume25
Issue number2
DOIs
Publication statusPublished - 1 Feb 2018
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Riva, F., Vianello, N., Spolaore, M., Ricci, P., Cavazzana, R., Marrelli, L., & Spagnolo, S. (2018). Three-dimensional simulations of plasma turbulence in the RFX-mod scrape-off layer and comparison with experimental measurements. Physics of Plasmas, 25(2), -. [022305]. https://doi.org/10.1063/1.5008803