Magnetic island control on the Compact Auburn Torsatron*
Abstract
The understanding and control of magnetic islands is an important issue in confinement of toroidal plasmas. A series of recent experiments on the Compact Auburn Torsatron (CAT) [Fusion Technol. 18, 281 (1990)] have investigated the control of magnetic islands. As a by-product, the minimization of the size of magnetic islands has been accomplished through the application of externally applied error fields. Both the phase and amplitude of the applied correction field at a given rational surface are varied in order to control the island chain on a rational surface. The experimental results have been interpreted within the framework of a Hamiltonian description of the magnetic field in toroidal geometry. In particular it has been demonstrated that first order perturbation theory is sufficient to predict the variation of island size for a wide range of externally applied fields. Using this theoretical approach a novel technique of error field determination through the measurement of the local rotational transform has been developed. The physical mechanisms which lead to spatial spreading of the electron beam used in the surface mapping have also been studied.
- Publication:
-
Physics of Plasmas
- Pub Date:
- May 1994
- DOI:
- 10.1063/1.870709
- Bibcode:
- 1994PhPl....1.1576G