First access to ELM-free negative triangularity at low aspect ratio

A. O. (ORCID:0000000296121936) Nelson, C. Vincent, H. Anand, J. (ORCID:0000000195653466) Lovell, J. F. (ORCID:0000000313287154) Parisi, H. S. (ORCID:0000000162602873) Wilson, K. (ORCID:0000000281282438) Imada, W. P. Wehner, M. Kochan, S. Blackmore, G. (ORCID:0000000308880105) McArdle, S. (ORCID:0000000164373752) Guizzo, L. Rondini, S. Freiberger, C. (ORCID:0000000150694934) Paz-Soldan

Research output: Contribution to journalArticlepeer-review

Abstract

A plasma scenario with negative triangularity (NT) shaping is achieved on MAST-U for the first time. While edge localized modes (ELMs) are eventually suppressed as the triangularity is decreased below δ ≲ − 0.06 , an extended period of H-mode operation with Type-III ELMs is sustained at less negative δ even through access to the second stability region for ideal ballooning modes is closed. This documents a qualitative difference from the ELM-free access conditions documented in NT scenarios on conventional aspect ratio machines. The electron temperature at the pedestal top drops across the transition to ELM-free operation, but a steady rise in core temperature as δ is decreased allows for similar normalized β in the ELM-free NT and H-mode positive triangularity shapes.

Original languageEnglish
JournalNuclear Fusion
Volume64
DOIs
StatePublished - 2024

Funding

FC02-04ER54698; SC0022272; SC0018991; AC05-00OR22725

Fingerprint

Dive into the research topics of 'First access to ELM-free negative triangularity at low aspect ratio'. Together they form a unique fingerprint.

Cite this