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Comparison of MHD Stability between Positive- and Negative-Triangularity Tokamak Plasmas with Internal Transport Barriers

Yusai MASAMOTO, Nobuyuki AIBA¹⁾ and Masaru FURUKAWA

Tottori University, 4-101 Minami, Koyama-cho, Tottori-shi, Tottori 680-8552, Japan

1)

National institutes for Quantum and Radiological Science and Technology (QST), Naka, Ibaraki 311-0193, Japan

(Received 10 January 2022 / Accepted 9 March 2022 / Published 13 May 2022)

Abstract

Ideal magnetohydrodynamics (MHD) stability of tokamak plasmas is compared between positive and negative triangularity cross sections. The bootstrap current is included that is determined from the density and temperature profiles. This is crucial for a DEMO reactor design. The density and temperature profiles are chosen to have internal transport barriers (ITBs), which are necessary if an H-mode edge cannot be expected. The ideal MHD stability is examined in a wide range of the ITB position and the central temperature. We confirmed that ballooning modes are prone to be unstable when the ITB is located near the plasma edge for negative triangularity. Internal kink modes become dominant instability when the ITB is located inner side of the plasma for both positive and negative triangularities. We have succeeded to stabilize both ballooning and internal kink modes by introducing additional currents to control the safety factor profiles in a favorable manner.

Copyright (c) 2022 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

DEMO reactor, internal transport barrier, negative triangularity, bootstrap current, ideal MHD stability

DOI: 10.1585/pfr.17.2403038

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