FusEdWeb: Fusion Energy Education

Glossary of Plasma Physics and Fusion Energy Research

Search         Submit an Entry

Browse Entries: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

See also the Plasma Dictionary.

  Term: Magnetic Island
  Definition: A magnetic topology near a "rational surface" (see entry) where the flux surface is broken up into tubes which are not connected with each other poloidally. Islands may develop in non-ideal magnetohydrodynamic fluids, where electrical resistance becomes important and magnetic field lines are no longer "frozen-in" to the fluid. Then magnetic tearing and reconnection may allow field lines to link up and form "islands" with a local magnetic axis (see entry) in a narrow region near a rational surface (see entry). (See also MHD, frozen-in law). The development of islands may be caused by a small perturbation, whether internal or external, whether deliberate or accidental, and is usually associated with enhanced transport (i.e., reduced confinement). The centers of the islands are magnetic O-points, while the boundaries between islands are marked by X-points (see entries).

Previous Next