The collisional drift wave instability in steep density gradient regimes

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The collisional drift wave instability in a straight magnetic field configuration is studied within a full-F gyro-fluid model, which relaxes the Oberbeck–Boussinesq (OB) approximation. Accordingly, we focus our study on steep background density gradients. In this regime we report on corrections by factors of order one to the eigenvalue analysis of former OB approximated approaches as well as on spatially localised eigenfunctions, that contrast strongly with their OB approximated equivalent. Remarkably, non-modal phenomena arise for large density inhomogeneities and for all collisionalities. As a result, we find initial decay and non-modal growth of the free energy and radially localised and sheared growth patterns. The latter non-modal effect sustains even in the nonlinear regime in the form of radially localised turbulence or zonal flow amplitudes.
Original languageEnglish
Article number026015
JournalNuclear Fusion
Issue number2
Number of pages7
Publication statusPublished - 2019
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Collisional (resistive, dissipative) drift wave instability, Non-Oberbek-Boussinesq effects, Full-F gyro/drift-fuid theory, large density inhomogenity, Steep background ndensit gradiant, Non-modal effects
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ID: 166593805