Modelling of electrostatic ion-scale turbulence in divertor tokamaks with the gyrokinetic code $$\mathrm{COGENT}$$

Journal Article · Wed Feb 16 00:00:00 EST 2022 · Contributions to Plasma Physics

DOI:https://doi.org/10.1002/ctpp.202100162· OSTI ID:1903437

Dorf, Mikhail ^[1]; Dorr, Milo ^[1]

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1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Here, continuum gyrokinetic simulations of electrostatic ion scale turbulence are presented for the case of a diverted (single-null) tokamak geometry. The simulation model, implemented in the finite-volume code COGENT, solves the long-wavelength limit of the full-F gyrokinetic equation for ion species coupled to a vorticity equation for electrostatic potential variations, where a fluid model is used for an electron response. The model describes the ion scale ion temperature gradient (ITG) and resistive drift modes as well as neoclassical ion physics effects. Different turbulence regimes are observed depending on the plasma profiles, and the roles of a self-consistent background electric field and an X-point geometry are explored. In particular, increasing the pedestal density gradient and the corresponding radial electric field is demonstrated to suppress the ITG turbulence, whereas the same edge plasma background can still be destabilized by the resistive modes when the plasma resistivity is increased. The effects of X-point geometry are assessed by comparing cross-separatrix simulations with counterpart calculations performed for a toroidal annulus geometry. For the simulation parameters considered, similar global behaviour is observed in both cases, whereas strong local suppression of turbulence fluctuations is demonstrated near the X-point for the case of a single-null geometry.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE; USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1903437
• Alternate ID(s): OSTI ID: 1845737
• Report Number(s): LLNL-JRNL-826823; 1041711
• Journal Information: Contributions to Plasma Physics, Journal Name: Contributions to Plasma Physics Journal Issue: 5-6 Vol. 62; ISSN 0863-1042
• Publisher: Wiley
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
finite-volume methods
gyrokinetics
tokamak edge