TY - JOUR
T1 - First access to ELM-free negative triangularity at low aspect ratio
AU - Nelson, A. O. (ORCID:0000000296121936)
AU - Vincent, C.
AU - Anand, H.
AU - Lovell, J. (ORCID:0000000195653466)
AU - Parisi, J. F. (ORCID:0000000313287154)
AU - Wilson, H. S. (ORCID:0000000162602873)
AU - Imada, K. (ORCID:0000000281282438)
AU - Wehner, W. P.
AU - Kochan, M.
AU - Blackmore, S.
AU - McArdle, G. (ORCID:0000000308880105)
AU - Guizzo, S. (ORCID:0000000164373752)
AU - Rondini, L.
AU - Freiberger, S.
AU - Paz-Soldan, C. (ORCID:0000000150694934)
PY - 2024
Y1 - 2024
N2 - 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.
AB - 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.
U2 - 10.1088/1741-4326/ad89db
DO - 10.1088/1741-4326/ad89db
M3 - Article
SN - 0029-5515
VL - 64
JO - Nuclear Fusion
JF - Nuclear Fusion
ER -