Achievement of FZJ Jointed International Collaboration Highlighted as Cover Story at the IOP journal ‘Plasma Science and Technology’
On August 4, 2021, the FZJ joint international collaboration titled “Application of 3D MHD equilibrium calculation to RMP experiments in the J-TEXT tokamak” has been published and highlighted as the cover story of PST Issue 8 2021.
Traditionally, as Tokamaks are often regarded as two-dimensional (2D) systems, we approach their physics using 2D methods. However, as Tokamaks have discrete toroidal field coils, they are subject to toroidal field ripples. Additionally, many Tokamak experiments feature resonant magnetic perturbation (RMP) coils to influence magnetohydrodynamic (MHD) instabilities, and to suppress or mitigate edge localized modes (ELMs). The application of RMP coils can break the initial axisymmetry and change the magnetic topology in Tokamak systems. To understand the plasma equilibrium response to the RMP fields, three-dimensional (3D) non-linear magnetohydrodynamics equilibrium calculations have been carried out for an RMP field-penetration experiment on J-TEXT by international joint efforts contributed from Huazhong University of Science and Technology (HUST), China, National Institute for Fusion Science (NIFS), Japan, and IEK-4, Forschungszentrum Jülich GmbH (FZJ), Germany. The results show that the effects driven by the redistribution of plasma pressure and current - due to the formation of magnetic islands at various resonant rational surfaces - should be considered self-consistently for correctly understanding changes in the magnetic structure. Such changes include changes in the shape and size of magnetic islands, as well as variations in the distribution of stochastic fields around the magnetic islands and at the plasma boundary, which plays an important role for plasma-wall interactions.
Liang