An explanation for hard MHD stability limits in low-<i>q</i> <sub>95</sub> diverted tokamak plasmas
Abstract This paper proposes a model attempting to explain the appearance of fast growing global disruptive instabilities in diverted configurations when the safety factor near the magnetic separatrix approaches two. We show that if edge density and pressure gradients are strong enough, although external kink modes are stable, poloidal harmonics may couple allowing for a global fluid perturbation to become unstable. The instability window is approached sharply as the mode resonance occurs in the edge region, and is characterised by rather large growth rates even with modest gradients.
Authors
- J. P. Graves (ORCID: https://orcid.org/0000-0002-7959-7959)
- D. Brunetti (ORCID: https://orcid.org/0000-0001-8650-3271)
- S. Saarelma (ORCID: https://orcid.org/0000-0002-6838-2194)
- Christopher Ham (ORCID: https://orcid.org/0000-0001-9190-8310)
Institutions
- United Kingdom Atomic Energy Authority (GB)
- École Polytechnique Fédérale de Lausanne (CH)
- University of York (GB)
Publication Details
- Journal
- Plasma Physics and Controlled Fusion
- Published
- 2025-08-08
- DOI
- https://doi.org/10.1088/1361-6587/adf997
- Primary Topic
- Magnetic confinement fusion research
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- EUROfusion
- European Commission
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Euratom Research and Training Programme
- Engineering and Physical Sciences Research Council