Modelling the Neoclassical Tearing Mode

Howard Wilson
Culham Science Center

The neoclassical tearing mode is an instability of the tokamak plasma that results in a change of the toroidal magnetic topology and a consequent loss in confinement. It is a concern for the performance of a burning plasma device like ITER.
The tearing mode causes coherent magnetic structures, or “islands” to be formed. The response of the plasma to these islands results in perturbed current density, which, for a sufficiently large island, causes it to grow. The calculation of the threshold island size, above which it grows, involves several phenomena including the effects of the ion orbits, and the interaction between the fine-scale turbulence and large scale island structure. This talk will introduce the basic physics lying behind the theory of the neoclassical tearing mode, and identify some of the key challenges for constructing a complete computational model.

Presentation (PowerPoint File)

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