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Magnetic island: Difference between revisions
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A magnetic island is a | A magnetic island is a closed magnetic flux tube (cf. [[Flux surface]]), bounded by a [[Separatrix|separatrix]], isolating it from the rest of space. | ||
Its topology is toroidal | Its topology is toroidal. | ||
In the context of magnetic confinement fusion, the basic magnetic field configuration consists of toroidally nested [[Flux surface|flux surfaces]], while each flux surface is characterised by a certain value of the [[Magnetic shear|rotational transform]] or safety factor ''q''. Magnetic islands can appear at flux surfaces with a rational value of the safety factor ''q = m/n''. | In the context of magnetic confinement fusion, the basic magnetic field configuration consists of toroidally nested [[Flux surface|flux surfaces]], while each flux surface is characterised by a certain value of the [[Magnetic shear|rotational transform]] or safety factor ''q''. Magnetic islands can appear at flux surfaces with a rational value of the safety factor ''q = m/n''. | ||
<ref>[http://dx.doi.org/10.1051/anphys:2004001 J.H. Misguich, J.-D. Reuss, D. Constantinescu, G. Steinbrecher, M. Vlad, F. Spineanu, B. Weyssow, R. Balescu, ''Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines'', Ann. Phys. Fr. '''28''' (2003) 1]</ref> | <ref>[http://dx.doi.org/10.1051/anphys:2004001 J.H. Misguich, J.-D. Reuss, D. Constantinescu, G. Steinbrecher, M. Vlad, F. Spineanu, B. Weyssow, R. Balescu, ''Noble internal transport barriers and radial subdiffusion of toroidal magnetic lines'', Ann. Phys. Fr. '''28''' (2003) 1]</ref> | ||
Subsidiary islands can appear within an island. | |||
== | == Island birth == | ||
The rupture of the original topology of toroidally nested flux surfaces needed to produce the island requires the reconnection of magnetic field lines, which can only occur with finite resistivity. | The rupture of the original topology of toroidally nested flux surfaces needed to produce the island requires the reconnection of magnetic field lines, which can only occur with finite resistivity. | ||