Simulation of MHD activity during density limit disruptions in tokamaks
The phenomenon of major disruptions in tokamaks is well known. Despite detailed experimental studies, the theoretical understanding has remained poor. In this paper numerical simulations are presented, as well as a theoretical model for major disruptions triggered by exceeding the density limit. The model contains as its main elements non-linear mode coupling induced by the presence of a large amplitude m=2/n=1 mode and non-linear interaction involving primarily the 2/1, 1/1 and 3/2 modes. The model is consistent with the experimental observation that a major disruption takes place in two steps. The simulations on which the model is based use the reduced-MHD equations together with an equation for the electron temperature including ohmic heating, radiation losses and highly anisotropic thermal conduction. The radiation losses are prescribed so as to match measurements on JET during a density limit disruption, and a neoclassical formula is used for the resistivity. A more detailed account of these simulations is given.
Bibliographic Reference: Article: Proceedings of the 18th European Conference on Controlled Fusion and Plasma Physics, Vol. 15C (1991) Part II, pp. 41-44
Record Number: 199210099 / Last updated on: 1994-12-02
Original language: en
Available languages: en