Progress in understanding disruptions triggered by massive gas injection via 3D non-linear MHD modelling with JOREK. (18th October 2016)

• Record Type: Journal Article
• Authors: Nardon, E; Fil, A; Hoelzl, M; Huijsmans, G
• Other Names: collab.
• Is Part Of: Plasma physics and controlled fusion. Volume 59:Number 1(2017:Jan.)
• Publication Date: 2016-10-18
• Subjects: disruption -- non-linear MHD modelling -- massive gas injection; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/0741-3335/59/1/014006
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: 3D non-linear MHD simulations of a D 2 massive gas injection (MGI) triggered disruption in JET with the JOREK code provide results which are qualitatively consistent with experimental observations and shed light on the physics at play. In particular, it is observed that the gas destabilizes a large m / n = 2/1 tearing mode, with the island O-point coinciding with the gas deposition region, by enhancing the plasma resistivity via cooling. When the 2/1 island gets so large that its inner side reaches the q = 3/2 surface, a 3/2 tearing mode grows. Simulations suggest that this is due to a steepening of the current profile right inside q = 3/2. Magnetic field stochastization over a large fraction of the minor radius as well as the growth of higher n modes ensue rapidly, leading to the thermal quench (TQ). The role of the 1/1 internal kink mode is discussed. An I p spike at the TQ is obtained in the simulations but with a smaller amplitude than in the experiment. Possible reasons are discussed.