Journal article · Preprint article
The collisional drift wave instability in steep density gradient regimes
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.
Language: | English |
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Year: | 2019 |
Pages: | 026015 |
ISSN: | 17414326 , 10185577 and 00295515 |
Types: | Journal article and Preprint article |
DOI: | 10.1088/1741-4326/aaf6cc |
ORCIDs: | Wiesenberger, Matthias , 0000-0001-8171-8038 and 0000-0002-4270-9160 |
Collisional (resistive, dissipative) drift wave instability Full-F gyro/drift-fuid theory Non-Oberbek-Boussinesq effects Non-modal effects Steep background ndensit gradiant large density inhomogenity