Zonal instability and wave trapping. Issue 1 (February 2021)

• Record Type: Journal Article
• Authors: Garbet, X.; Panico, O.; Varennes, R.; Gillot, C.; Dif-Pradalier, G.; Sarazin, Y.; Bourne, E.; Grandgirard, V.; Ghendrih, P.; Zarzoso, D.; Vermare, L.
• Is Part Of: Journal of physics. Volume 1785:Issue 1(2021)
• Publication Date: 2021-02
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/1785/1/012002
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: This paper presents a model for zonal flow generation based on a wave kinetic equation coupled to a poloidal momentum equation in a regime where wave trapping matters. Several models of the wave collision operator have been tested: Krook, diffusion and diffusion plus an instability growth rate. Conditions for zonal instability have been identified. It is found that a zonal instability is possible in all cases. However the force is a power law of the zonal velocity, so different from the quasi-linear case of random phases that produces a force that is linear in velocity. Also the zonal force may change sign, leading to flow radial profiles that are not sinusoidal.