Quantification of Turbulent Driving Forces for the Geodesic Acoustic Mode in the JFT-2M Tokamak

T Kobayashi; M Sasaki; T Ido; K Kamiya; Y Miura; Y Nagashima; K Ida; S Inagaki; A Fujisawa; S-I Itoh; K Itoh

doi:10.1103/PhysRevLett.120.045002

Quantification of Turbulent Driving Forces for the Geodesic Acoustic Mode in the JFT-2M Tokamak

Phys Rev Lett. 2018 Jan 26;120(4):045002. doi: 10.1103/PhysRevLett.120.045002.

Authors

T Kobayashi¹, M Sasaki^{2

3}, T Ido¹, K Kamiya⁴, Y Miura⁵, Y Nagashima^{2

3}, K Ida^{1

3}, S Inagaki^{2

3}, A Fujisawa^{2

3}, S-I Itoh^{2

3}, K Itoh^{1

3

6}

Affiliations

¹ National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan.
² Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan.
³ Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan.
⁴ National Institutes for Quantum and Radiological Science and Technology, Naka 311-0193, Japan.
⁵ Japan Atomic Energy Agency, Naka 311-0193, Japan.
⁶ Institute of Science and Technology Research, Chubu University, Kasugai 487-8501, Japan.

PMID: 29437414
DOI: 10.1103/PhysRevLett.120.045002

Abstract

We investigate spatial structures of turbulence and turbulent transport modulated by the geodesic acoustic mode (GAM), from which the excitation mechanism of the GAM is discussed. The GAM is found to be predominantly excited through a localized Reynolds stress force, rather than the dynamic shearing force. The evaluated growth rate is larger than the linear damping coefficients and is on the same order of magnitude as the effective growth rate evaluated from time evolution in the GAM kinetic energy.