TOROIDAL MINIMUM-B AND RELATED MHD EQUILIBRIA
Minimum-B mirror systems provide plasma stability but are subject to loss through the magnetic mirrors. Such losses are absent in systems with toroidal magnetic surfaces but it is well known that vacuum magnetic fields with toroidal minimum-B flux surfaces do not exist. Despite this, the authors constructed a set of finite beta toroidal minimum-B equilibria (in which toroidal magnetic surfaces coincide with constant-B contours and in which B increases and p decreases with distance from the magnetic axis). These are the only possible axisymmetric minimum-B toroidal equilibria and are compatible with the vacuum field result because they have no low-beta limit. They are members of a family of equilibria all of which correspond to a single set of magnetic surfaces. This set of magnetic surfaces is unique and is determined by a novel approach to the Grad-Shafranov equation. In these configurations all guiding centre drifts lie in the magnetic surface, so they have no neoclassically enhanced transport and they are free of all trapped particle effects. Unfortunately, however, they do not share the intrinsic stability properties of their mirror counterparts.
Bibliographic Reference: WRITE TO THE LIBRARIAN, UKAEA, CULHAM LABORATORY, ABINGDON, OXON OX14 3DB (UK), MENTIONING REPORT CLM-P743, 1985
Record Number: 1989124039800 / Last updated on: 1987-01-01
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