Title: Sawtooth suppression by flux pumping on HBT-EP

Abstract

Abstract This study examines the mechanisms underlying sawtooth suppression in the High Beta Tokamak-Extended Pulse (HBT-EP) device. It is observed that strong-intensity sawtooth activities correlate with reduced-amplitude magnetohydrodynamics (MHD) edge modes which are identified as $m/n=3/1$ external kink modes, while sawtooth suppression correlates with larger and saturated edge mode amplitudes. To further investigate these correlations, the plasma–wall coupling was manipulated by adjusting the positions of the conducting walls in HBT-EP. It was found that strong sawtooth events occur when the normalized wall radius $b/a$ is within a critical value. This implies that the plasma–wall distance must be sufficiently small to ensure effective stabilization of the edge mode. Even slight differences in major radius result in significantly different discharge styles, categorized as ‘sawtoothing discharges’ and ‘sawtooth-suppressed discharges’ respectively. Through a series of mode structure analyses, we confirm the coexistence and coupling of the $m/n=1/1$ helical core, $m/n=2/1$ tearing mode, and $m/n=3/1$ external kink mode during sawtooth-suppression, and that this coupling induces anomalous current broadening. Based on these findings, we conclude that sawtooth suppression in the HBT-EP tokamak is consistent with the process of magnetic flux pumping.

Authors:

Li, Boting ;

• Search DOE PAGES for author "Li, Boting"
• Search DOE PAGES for ORCID "0009-0002-3323-5781"

Levesque, J. P. ;

• Search DOE PAGES for author "Levesque, J. P."
• Search DOE PAGES for ORCID "0000-0003-1193-475X"

Navratil, G. A. ;

• Search DOE PAGES for author "Navratil, G. A."
• Search DOE PAGES for ORCID "0000-0002-2930-5196"

Mauel, M. E.

• Search DOE PAGES for author "Mauel, M. E."
• Search DOE PAGES for ORCID "0000-0003-2490-7478"

Publication Date:

Thu Feb 29 00:00:00 EST 2024

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES)

OSTI Identifier:

2316068

Alternate Identifier(s):

OSTI ID: 2309771

Grant/Contract Number:  

FG02-86ER53222

Resource Type:

Published Article

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Name: Nuclear Fusion Journal Volume: 64 Journal Issue: 4; Journal ID: ISSN 0029-5515

Publisher:

IOP Publishing

Country of Publication:

IAEA

Language:

English