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Magnetic island: Difference between revisions
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If the ambient magnetic field (produced by external coils) has an appropriate structure, the island can also lock onto that structure. | If the ambient magnetic field (produced by external coils) has an appropriate structure, the island can also lock onto that structure. | ||
<ref>[http://link.aps.org/doi/10.1103/PhysRevLett.78.1703 F.L. Waelbroeck and R. Fitzpatrick, ''Rotation and Locking of Magnetic Islands'', Phys. Rev. Lett. '''78''' (1997) 1703–1706]</ref> | <ref>[http://link.aps.org/doi/10.1103/PhysRevLett.78.1703 F.L. Waelbroeck and R. Fitzpatrick, ''Rotation and Locking of Magnetic Islands'', Phys. Rev. Lett. '''78''' (1997) 1703–1706]</ref> | ||
Locked island often lead to a [[Disruption|disruption]] (complete loss of confinement) in [[Tokamak|tokamaks]]. | |||
== Transport effects == | == Transport effects == | ||
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The interaction of neighbouring island chains causes the magnetic field to become stochastic (according to the Chirikov criterion <ref>[http://dx.doi.org/10.1016/0370-1573(79)90023-1 B.V. Chirikov, ''A universal instability of many-dimensional oscillator systems'', Phys. Rep. '''52''', Issue 5 (1979) 263]</ref>), resulting in enhanced (anomalous) radial transport. | The interaction of neighbouring island chains causes the magnetic field to become stochastic (according to the Chirikov criterion <ref>[http://dx.doi.org/10.1016/0370-1573(79)90023-1 B.V. Chirikov, ''A universal instability of many-dimensional oscillator systems'', Phys. Rep. '''52''', Issue 5 (1979) 263]</ref>), resulting in enhanced (anomalous) radial transport. | ||
<ref>C.W. Horton, Y.H. Ichikawa, ''Chaos and structures in nonlinear plasmas'', World Scientific, 1996 ISBN 9789810226367</ref> | <ref>C.W. Horton, Y.H. Ichikawa, ''Chaos and structures in nonlinear plasmas'', World Scientific, 1996 ISBN 9789810226367</ref> | ||
== Island control == | |||
Island control is possible by tailoring the ''q''-profile, external magnetic fields, | |||
<ref>[http://dx.doi.org/10.1088/0741-3335/44/7/323 S.R. Hudson et al, Plasma Phys. Control. Fusion '''44''' (2002) 1377]</ref> | |||
and the pressure profile. | |||
Pressure effects can lead to 'island healing'. | |||
<ref>[http://dx.doi.org/10.1088/0029-5515/45/7/006 R. Kanno et al, Nucl. Fusion '''45''' (2005) 588]</ref> | |||
Active control of islands by external means is also possible (cf. the 'Seek and destroy' technique, under development <ref>[http://www.rijnhuizen.nl/en/node/195 Seek and Destroy System for magnetic island control]</ref>). | |||
== See also == | == See also == | ||