Year: 2024
Type: article
Abstract: At the DIII-D tokamak, plasmas with negative triangularity (NT) have been found to have similar energy confinement times as H-mode plasmas with positive triangularity. These NT plasmas also have a stable edge that inhibits H-mode, lacks dangerous edge transients, and has naturally low impurity confinement. For these reasons, NT plasmas have the potential to be a transformative reactor scenario. To determine the importance of strong co-current neutral beam torque for NT performance at DIII-D, scans of neutral beam torque at constant neutral beam power have been performed. These scans have shown that the energy confinement time for a basic, inductive NT scenario ( q 95 ≈ 2.8 ) decreases by 16% when torque is reduced to reactor levels. This reduction in confinement can be replicated with gyrofluid modeling that isolates the role of E × B shear in the change in transport. In a separate set of discharges with lower plasma current ( q 95 ≈ 4.2 ), no significant correlation between confinement time and rotation was found. Throughout this investigation, excellent MHD stability was observed, even with very low toroidal rotation. Further, low impurity confinement was found at multiple rotation levels. Throughout the campaign, rotation near the edge was counter-current, consistent with the measurement of counter-current intrinsic edge rotation, and these observations agree with NT results from the TCV tokamak.
Institution: General Atomics (United States)
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: MHD MODE CONTROL RESEARCH IN DIII-D, G1273338650, G222768804, G2730808397, G333530719, G372272130, THE DIII-D NATIONAL FUSION PROGRAM AND ADVANCED FUSION TECHNOLOGY RESEARCH AND DEVELOPMENT, PROPOSED DIAGNOSTICS & PHYSICS CONTRIBUTIONS OF THE UNIV OF TX FUSION RESEARCH CENTER TO THE DIII-D, DISRUPTION AND ELM CONTROL RESEARCH IN THE DIII-D TOKAMAK, MEASUREMENT OF HELICONS AND PARAMETRIC DECAY WAVES IN DIII-D WITH PHASE CONTRAST IMAGING, G5188626685, PROPOSED DIAGNOSTICS AND PHYSICS CONTRIBUTIONS OF THE UNIVERSITY OF TEXAS FUSION RESETRAVICENTER TO THE DIII-D PROGRAM, DISRUPTION AND ELM CONTROL RESEARCH IN THE DIII-D TOKAMAK, PROPOSED DIAGNOSTICS & PHYSICS CONTRIBUTIONS OF THE UNIV OF TX FUSION RESEARCH CENTER TO THE DIII-D, MEASUREMENT OF HELICONS AND PARAMETRIC DECAY WAVES IN DIII-D WITH PHASE CONTRAST IMAGING, THE DIII-D NATIONAL FUSION PROGRAM AND ADVANCED FUSION TECHNOLOGY RESEARCH AND DEVELOPMENT, G7473577905, THE DIII-D FUSION RESEARCH PROGRAM AND ADVANCED FUSION TECHNOLOGY RESEARCH AND DEVELOPMENT, MHD MODE CONTROL RESEARCH IN DIII-D, MHD MODE CONTROL RESEARCH IN DIII-D
OpenAlex ID: W4401448064