Edge Radial Electric Field in Positive and Negative Triangularity Plasmas in the TCV Tokamak

S. Rien\"acker; P. Hennequin; L. Vermare; C. Honor\'e; R. Bouffet-Klein; S. Coda; B. Labit; B. Vincent; K.E. Thome; O. Krutkin; A. Balestri; Y. Nakeva; the TCV team

arXiv:2507.08682·physics.plasm-ph·July 14, 2025

Edge Radial Electric Field in Positive and Negative Triangularity Plasmas in the TCV Tokamak

S. Rien\"acker, P. Hennequin, L. Vermare, C. Honor\'e, R. Bouffet-Klein, S. Coda, B. Labit, B. Vincent, K.E. Thome, O. Krutkin, A. Balestri, Y. Nakeva, the TCV team

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TL;DR

This study reports the first measurements of edge radial electric fields in negative triangularity plasmas in the TCV tokamak, revealing stronger electric field wells and shear compared to positive triangularity plasmas, which may relate to improved plasma performance.

Contribution

First measurement of edge $E_r$ in negative triangularity TCV plasmas showing significant differences from positive triangularity configurations.

Findings

01

Stronger $E_r$ wells in NT plasmas across various heating methods.

02

Enhanced $E_r imes B$ shear in NT plasmas.

03

Potential link between $E_r$ features and NT performance gains.

Abstract

We present the first edge $E_{r}$ measurements in negative triangularity (NT) TCV plasmas. The Doppler backscattering measurements of $v_{⊥} \approx E_{r} / B$ reveal a significant impact of triangularity on the $E_{r}$ well: In Ohmic, NBI, and ECRH heated discharges, the $E_{r}$ well and associated $E_{r} \times B$ shear are stronger in NT-shaped plasmas compared to their positive triangularity (PT) counterpart. This suggests a connection to the concomitant NT performance gain relative to PT L-mode.

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