April 15-17

Abstract Details

files Add files

Abstracts

Author: Di Qi
Requested Type: Pre-Selected Invited
Submitted: 2019-02-20 14:39:45

Co-authors: A.J. Majda, A.J. Cerfon

Contact Info:
Courant Institute NYU
251 Mercer Street WWH 1011
New York, NY   10012-1
US

Abstract Text:
We present a new reduced fluid model for the study of the drift wave-zonal flow dynamics in magnetically confined plasmas. Our model can be viewed as an extension of the classic Hasegawa-Wakatani (HW) model and is based on an improved treatment of the electron dynamics parallel to the field lines, to guarantee a balanced electron flux on the magnetic surfaces. Our flux-balanced HW (bHW) model contains the same drift-wave instability as previous HW models, but also has unique features which distinguish it from these models: 1) it converges exactly to the modified Hasegawa-Mima model in the collisionless limit; 2) zonal structures are always present in the flux-balanced model, even for high resistivity, and strongly reduce the level of particle and vorticity flux; 3) the more robust zonal jets also have a higher variability, which is further enhanced when the computational domain is chosen to be elongated in the radial direction.

The case in which the computational domain is elongated in the radial direction is particularly interesting for another reason: we observe the emergence of complex multi-scale dynamics, with multiple jets interacting with one another, and intermittent bursts. These results present new challenges for theories attempting to predict the scale length of zonal jets in magnetized plasmas.

Comments: