The collisional drift wave instability in steep density gradient regimes

Nuclear Fushion

article

M. Held¹  M. Wiesenberger²  A. Kendl¹ 

[1] Institute for Ion Physics and Applied Physics, Universität Innsbruck;Department of Physics, Technical University of Denmark

关键词: collisional (resistive;    dissipative) drift wave instability;    non-Oberbeck–Boussinesqeffects;    full-F gyro/drift-fluid theory;    large density inhomogeneity;    steep background densitygradient;    non-modal effects;   

DOI  :  10.1088/1741-4326/aaf6cc

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown