Abstract: In the past, aspects of linearized ideal MHD stability, e.g. the vacuum field magnetic well, reduced parallel current density, or Mercier's criterion, were targeted for in the optimization of stellarator experiments such as W7-X and HSX. In this tutorial, the stability of plasma equilibria is discussed based on the energy principle of ideal MHD in the form of global mode analyses and local stability criteria. The field-line ballooning equation and Mercier's criterion are derived. Example applications typical for various classes of equilibria (tokamak, stellarator, weak or medium magnetic shear) are used to point out relationships between the violation of the local stability criteria and the spatial structure of global modes aiming at a categorization of ideal MHD stability limits. In the light of experimental results of the W7-AS stellarator and of the LHD torsatron, experiments are planned in W7-X to clarify the question of how important ideal MHD is in stellarator optimization.
Talk time in other timezones: AEST 12:00 AM Fri 26 May, JST 11:00 PM Thu 25 May, CEST 4:00 PM Thu 25 May, BST 3:00 PM Thu 25 May, UTC 14:00 Thu 25 May, EDT 10:00 AM Thu 25 May, CDT 9:00 AM Thu 25 May, MDT 8:00 AM Thu 25 May, MST 7:00 AM Thu 25 May