Abstract
We investigate the impact of toroidal rotation on axisymmetric MHD equilibria analytically and numerically, with a focus on the change of the safety factor and magnetic shear induced by the flow. When the toroidal rotation is radially localized by an external momentum source, the pressure due to the flow can change the magnetic configuration and the safety factor significantly, even for subsonic flows. Specifically, when the radial profile of the safety factor is not conserved throughout a discharge, toroidal flow can lead to magnetic shear reversal for the equilibrium magnetic field, and we find that the magnitude of the negative shear is amplified for cross sections with large negative triangularity. This has implications for both magnetohydrodynamic stability and anomalous transport. Furthermore, even when the magnetic flux is conserved and the radial magnetic shear profile does not change, the toroidal flow can modify the local magnetic shear. The poloidal variations of the local magnetic shear due to the flow can stabilize magnetohydrodynamic ballooning modes.
| Original language | English (US) |
|---|---|
| Article number | 105007 |
| Journal | Plasma Physics and Controlled Fusion |
| Volume | 61 |
| Issue number | 10 |
| DOIs | |
| State | Published - Sep 4 2019 |
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Keywords
- magnetic shear
- MHD equilibrium
- plasma equilibrium shape
- tokamak
- toroidal rotation
ASJC Scopus subject areas
- Nuclear Energy and Engineering
- Condensed Matter Physics
Cite this
Magnetic shear due to localized toroidal flow shear in tokamaks. / Lee, Jungpyo; Cerfon, Antoine.
In: Plasma Physics and Controlled Fusion, Vol. 61, No. 10, 105007, 04.09.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Magnetic shear due to localized toroidal flow shear in tokamaks
AU - Lee, Jungpyo
AU - Cerfon, Antoine
PY - 2019/9/4
Y1 - 2019/9/4
N2 - We investigate the impact of toroidal rotation on axisymmetric MHD equilibria analytically and numerically, with a focus on the change of the safety factor and magnetic shear induced by the flow. When the toroidal rotation is radially localized by an external momentum source, the pressure due to the flow can change the magnetic configuration and the safety factor significantly, even for subsonic flows. Specifically, when the radial profile of the safety factor is not conserved throughout a discharge, toroidal flow can lead to magnetic shear reversal for the equilibrium magnetic field, and we find that the magnitude of the negative shear is amplified for cross sections with large negative triangularity. This has implications for both magnetohydrodynamic stability and anomalous transport. Furthermore, even when the magnetic flux is conserved and the radial magnetic shear profile does not change, the toroidal flow can modify the local magnetic shear. The poloidal variations of the local magnetic shear due to the flow can stabilize magnetohydrodynamic ballooning modes.
AB - We investigate the impact of toroidal rotation on axisymmetric MHD equilibria analytically and numerically, with a focus on the change of the safety factor and magnetic shear induced by the flow. When the toroidal rotation is radially localized by an external momentum source, the pressure due to the flow can change the magnetic configuration and the safety factor significantly, even for subsonic flows. Specifically, when the radial profile of the safety factor is not conserved throughout a discharge, toroidal flow can lead to magnetic shear reversal for the equilibrium magnetic field, and we find that the magnitude of the negative shear is amplified for cross sections with large negative triangularity. This has implications for both magnetohydrodynamic stability and anomalous transport. Furthermore, even when the magnetic flux is conserved and the radial magnetic shear profile does not change, the toroidal flow can modify the local magnetic shear. The poloidal variations of the local magnetic shear due to the flow can stabilize magnetohydrodynamic ballooning modes.
KW - magnetic shear
KW - MHD equilibrium
KW - plasma equilibrium shape
KW - tokamak
KW - toroidal rotation
UR - http://www.scopus.com/inward/record.url?scp=85072709536&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85072709536&partnerID=8YFLogxK
U2 - 10.1088/1361-6587/ab3a7f
DO - 10.1088/1361-6587/ab3a7f
M3 - Article
AN - SCOPUS:85072709536
VL - 61
JO - Plasma Physics and Controlled Fusion
JF - Plasma Physics and Controlled Fusion
SN - 0741-3335
IS - 10
M1 - 105007
ER -