Effects of edge biasing on blob dynamics and associated transport in the edge of the J-TEXT tokamak

2022 ◽  
Author(s):  
Wei Li ◽  
Yuhong Xu ◽  
Jun Cheng ◽  
Hai Liu ◽  
Zhipeng Chen ◽  
...  
Keyword(s):  
Electric Field ◽  
Large Scale ◽  
Turbulent Transport ◽  
Radial Electric Field ◽  
Plasma Confinement ◽  
Flow Shear ◽  
Theoretical Predictions ◽  
Outward Motion ◽  
Electrode Biasing ◽  
Particle Confinement

Abstract Effects of edge radial electric field Er and Er × B flow shear on edge turbulence and turbulent transport, in particular, on large-scale blobs and blobby transport have been investigated in the positive and negative biasing discharges in the J-TEXT tokamak. The results show that under certain conditions, the positive electrode biasing induces better plasma confinement than the negative biasing. Further studies reveal that in addition to flow shear effects on blob dynamics, the local radial electric field at the edge region plays a significant role in repulsion of the blobs and associated transport, leading to improvement of particle confinement when the outward motion of the blobs is blocked. The results are in accordance with theoretical predictions.

scholarly journals Formation of the radial electric field profile in the WEST tokamak

2021 ◽  
Author(s):  
Laure Vermare ◽  
Pascale Hennequin ◽  
Cyrille Honore ◽  
Mathieu Peret ◽  
Guilhem Dif-Pradalier ◽  
...  
Keyword(s):  
Velocity Profile ◽  
Electric Field ◽  
Turbulent Transport ◽  
Radial Profile ◽  
Radial Electric Field ◽  
Turbulent Structures ◽  
The West ◽  
Transport Barrier ◽  
Deep Well ◽  
Electric Field Profile

Abstract Sheared flows are known to reduce turbulent transport by decreasing the correlation length and/or intensity of turbulent structures. The transport barrier that takes place at the edge during improved regimes such as H mode, corresponds to the establishment of a large shear of the radial electric field. In this context, the radial shape of the radial electric field or more exactly of the perpendicular $E\times B$ velocity appears as a key element in accessing improved confinement regimes. In this paper, we present the radial profile of the perpendicular velocity measured using Doppler back-scattering system at the edge of the plasma, dominated by the $E\times B$ velocity, during the first campaigns of the WEST tokamak. It is found that the radial velocity profile is clearly more sheared in LSN than in USN configuration for ohmic and low current plasmas ($B=3.7T$ and $q_{95}=4.7$), consistently with the expectation comparing respectively “favourable” versus “unfavourable” configuration. Interestingly, this tendency is sensitive to the plasma current and to the amount of additional heating power leading to plasma conditions in which the $E\times B$ velocity exhibits a deeper well in USN configuration. For example, while the velocity profile exhibits a clear and deep well just inside the separatrix concomitant with the formation of a density pedestal during L-H transitions observed in LSN configuration, deeper $E_r$ wells are observed in USN configuration during similar transitions with less pronounced density pedestal.

Influence of Radial Electric Field on High-Beta Plasma Confinement in the Gas Dynamic Trap

2007 ◽  
Vol 51 (2T) ◽  
pp. 340-342 ◽  
Author(s):  
P.A. Bagryansky ◽  
A.D. Beklemishev ◽  
E.I. Soldatkina
Keyword(s):  
Electric Field ◽  
Radial Electric Field ◽  
Plasma Confinement ◽  
Gas Dynamic ◽  
High Beta

Inward Turbulent Transport Produced by Positively Sheared Radial Electric Field in Stellarators

2000 ◽  
Vol 84 (26) ◽  
pp. 6042-6045 ◽  
Author(s):  
M. G. Shats ◽  
K. Toi ◽  
K. Ohkuni ◽  
Y. Yoshimura ◽  
M. Osakabe ◽  
...  
Keyword(s):  
Electric Field ◽  
Turbulent Transport ◽  
Radial Electric Field

Generation of Radial Electric Field with Electrode Biasing

2001 ◽  
Vol 18 (2) ◽  
pp. 257-259 ◽  
Author(s):  
Wang Cheng ◽  
Pan Ge-Sheng ◽  
Wen Yi-Zhi ◽  
Yu Chang-Xuan ◽  
Wan Shu-De ◽  
...  
Keyword(s):  
Electric Field ◽  
Radial Electric Field ◽  
Electrode Biasing
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