Reactor-relevant characteristics of DIII-D negative triangularity discharges
Abstract
A highlight of DIII-D experiments with negative triangularity (NT) shaped discharges was H-mode level confinement at significantly high beta with L-mode edge conditions. Beyond the favorable energy confinement, indications of improved momentum confinement were observed in NT discharges compared to matched positive triangularity (PT) cases. Co-NBI-heated discharges had higher core rotation and rotational shear than predicted from scaling laws while ECH-dominant discharges had toroidal rotation within the expected range. Additionally, a comparison of bootstrap current between equivalent discharges showed somewhat higher bootstrap current that is more broadly distributed and without a peak at the edge in NT over PT Also, NT discharges exhibit 30-60% higher Shafranov shift than PT for the same plasma pressure. Overall the many positive characteristics of negative triangularity plasmas, with prospects for low consequence ELMs and a low-field side divertor, make it an attractive option for a reactor.
Work supported by the US DOE under DE-FG02-97ER54415 and DE-FC02-04ER54698.- Publication:
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APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..DPPB10003A