The effect of curvature induced broken potential vorticity conservation on drift wave turbulences

Journal Article · 18 February 2021 · Plasma Physics and Controlled Fusion

DOI:https://doi.org/10.1088/1361-6587/abe24c· OSTI ID:1849556

Liu, Z. Y.; Zhang, Y. Z.; Mahajan, S. M.

Abstract

The correlation theory of turbulence suppression (Zhang and Mahajan 1993Phys. FluidsB52000) by velocity shear was constructed by invoking the ansatz of potential vorticity conservation (PVC) that holds for relatively simple (slab) models of drift wave turbulence. It is, therefore, surprising that a detailed modern simulation of the H mode pedestal, using the gyrokinetic code GENE (Hatchet al2018Plasma Phys. Control. Fusion60084003), found ‘striking agreement’ with the predictions of the analytic model. To understand the reasons for this remarkable agreement, an extended theory that contains finite (magnetic) curvature, and which does not conserve potential vorticity, is developed and ‘solved’ by calculating an inhomogeneous Green function reflecting the fact that the new system has a potential vorticity source. It is, then, demonstrated that the effect of the broken PVC is insignificant for the normal operation parameters in tokamaks; the correction due to curvature is at the order of $\left(2L_0/R\right)$, where $L_0$is the scale length of the local gradient and $R$is the major radius. The excellent agreement between simulation and slab model 1993 theory is therefore not accidental; the latter can be applied with confidence to the tokamak pedestal.

• Research Organization: Univ. of Texas, Austin, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: FG02-04ER54742
• OSTI ID: 1849556
• Journal Information: Plasma Physics and Controlled Fusion, Vol. 63, Issue 4; ISSN 0741-3335
• Publisher: IOP Science
• Country of Publication: United States
• Language: English

Related Subjects

Physics