Impact of magnetic drift configuration on the edge radial electric field in the TCV tokamak
Abstract
The edge radial electric (Er) in the Tokamak à Configuration Variable (TCV) is compared in matched L-mode discharges with opposite ion magnetic drift directions (favorable versus unfavorable B × ∇ B configurations). As previously reported on the WEST and AUG tokamaks, the Er profile---measured by Doppler backscattering (DBS)---exhibits a "well" just inside the separatrix in the favorable drift case, which is absent or less pronounced in the unfavorable counterpart. This observation holds over a broad range of plasma conditions, notably also in Ohmic discharges with nearly identical edge density and temperature profiles. Density fluctuation characteristics inferred from DBS are not drastically different: Under Ohmic heating, edge fluctuation levels tend to be higher in the favorable configuration, while radial correlation lengths are similar. The edge Er difference appears uncorrelated with carbon toroidal rotation behavior. Reducing density, or increasing auxiliary heating power tends to accentuate the edge Er disparity. Plasma current has little impact on both favorable and unfavorable Er profiles---in contrast to results from WEST. Approaching the L-H transition via auxiliary heating, edge Er × B shear and pressure grow more readily in the favorable configuration, and DBS fluctuation levels are reduced relative to the unfavorable case. Overall, our results confirm that the edge Er sensitivity to magnetic drift configuration is a robust, multi-machine phenomenon, with a plausible connection to confinement level and H-mode access.
Related
- Geodesic Acoustic Modes in pair plasmas confined in tokamak magnetic fields
- An Inverse Grad-Shafranov Neural Network Approach to Tokamak Magnetic Control
- Turbulent Origin of the Edge Radial Electric Field Asymmetry between Favourable and Unfavourable Drift Configurations
- Solar Magnetic Configuration Control over Radiation Belt Electrons
- Enhanced plasma production by ambipolar electric fields in convergent magnetic fields
BibTeX
@misc{rienacker2026impact,
title = {{Impact of magnetic drift configuration on the edge radial electric field in the TCV tokamak}},
author = {S. Rienäcker and L. Vermare and P. Hennequin and C. Honoré and B. Labit and S. Coda and L. Frassinetti and B. Vincent and O. Panico and Y. Wang and K. Singh},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.31424},
eprint = {2609.31424},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.31424},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Impact of magnetic drift configuration on the edge radial electric field in the TCV tokamak
AU - S. Rienäcker
AU - L. Vermare
AU - P. Hennequin
AU - C. Honoré
AU - B. Labit
AU - S. Coda
AU - L. Frassinetti
AU - B. Vincent
AU - O. Panico
AU - Y. Wang
AU - K. Singh
PY - 2026
DA - 2026/09/25
PB - arXiv
DO - 10.48550/arxiv.2609.31424
UR - https://arxiv.org/abs/2609.31424
AB - The edge radial electric (E_r) in the Tokamak à Configuration Variable (TCV) is compared in matched L-mode discharges with opposite ion magnetic drift directions (favorable versus unfavorable B × ∇ B configurations). As previously reported on the WEST and AUG tokamaks, the E_r profile---measured by Doppler backscattering (DBS)---exhibits a "well" just inside the separatrix in the favorable drift case, which is absent or less pronounced in the unfavorable counterpart. This observation holds over a broad range of plasma conditions, notably also in Ohmic discharges with nearly identical edge density and temperature profiles. Density fluctuation characteristics inferred from DBS are not drastically different: Under Ohmic heating, edge fluctuation levels tend to be higher in the favorable configuration, while radial correlation lengths are similar. The edge E_r difference appears uncorrelated with carbon toroidal rotation behavior. Reducing density, or increasing auxiliary heating power tends to accentuate the edge E_r disparity. Plasma current has little impact on both favorable and unfavorable E_r profiles---in contrast to results from WEST. Approaching the L-H transition via auxiliary heating, edge E_r × B shear and pressure grow more readily in the favorable configuration, and DBS fluctuation levels are reduced relative to the unfavorable case. Overall, our results confirm that the edge E_r sensitivity to magnetic drift configuration is a robust, multi-machine phenomenon, with a plausible connection to confinement level and H-mode access.
ER -