April 15-17

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Abstracts

Author: Hongxuan Zhu
Requested Type: Pre-Selected Invited
Submitted: 2019-02-19 12:43:25

Co-authors: Yao Zhou, I. Y. Dodin

Contact Info:
Princeton University
Princeton Plasma Physics Lab
Princeton, NJ   08540
United States

Abstract Text:
Zonal flows (ZFs) can be generated by drift waves (DWs), and they can also be destroyed by DWs. The latter process is often called the tertiary instability (TI) and can be realized via two different mechanisms. One is the Kelvin--Helmholtz instability; but we have shown that it is, in fact, absent for large-scale ZFs [1-3]. The more relevant mechanism seems to be the ZF-induced modification of the primary-instability growth rate. Here, we propose a new way to describe this process using an improved wave-kinetic equation (WKE) for the modified Terry--Horton model [4]. We show that the DW diffraction is needed to maintain the TI-mode structure. The resulting theory seems to capture the Dimits shift and may eventually allow us to describe it quantitatively. An extension of this theory to the Hasegawa--Wakatani model [5] is also presented.
[1] H. Zhu, Y. Zhou, D. E. Ruiz, and I. Y. Dodin, Phys. Rev. E 97,
053210 (2018).
[2] H. Zhu, Y. Zhou, and I. Y. Dodin, Phys. Plasmas 25, 072121 (2018).
[3] H. Zhu, Y. Zhou, and I. Y. Dodin, Phys. Plasmas 25, 082121 (2018).
[4] D. A. St-Onge, J. Plasma Phys. 83, 905830504 (2017).
[5] R. Numata, R. Ball, and R. L. Dewar, Phys. Plasmas 14, 102312 (2007).
***This work was supported by the U.S. Department of Energy (DOE),
Office of Science, Office of Basic Energy Sciences, and also by the U.S. DOE through Contract No. DE-AC02-09CH11466.

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