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{{Noref|date=April 2013}}
{{About|the physical concept|philosophical concepts|Fluxon (philosophy)}}

In [[physics]], a '''fluxon''' is a [[quantum]] of [[flux|electromagnetic flux]].  The term may have any of several related meanings.

==Superconductivity==
In the context of [[superconductivity]], especially related to [[type II superconductor]], a fluxon (aka [[Abrikosov vortex]]) is a small whisker of normal phase surrounded by superconducting phase. [[Supercurrent]]s circulate around its center. The magnetic field through such a whisker and its neighborhood, which has size of the order of London penetration depth <math>\lambda_L</math> (~100 nm), is quantized because of the phase properties of the [[magnetic potential|magnetic]] [[vector potential]] in [[quantum electrodynamics]], see [[magnetic flux quantum]] for details.

In the context of [[long Josephson junction]]s, a '''fluxon''' (aka [[Josephson vortex]]) is made of circulating [[supercurrent]]s and has ''no'' normal core. Supercurrents circulate just around the mathematical center of a fluxon, which is situated with the (insulating) Josephson barrier. Again, the magnetic flux created by circulating [[supercurrent]]s is equal to a [[magnetic flux quantum]] <math>\Phi_0</math> (or a bit less if the superconducting electrodes of the Josephson junction are thinner than <math>\lambda_L</math>).

==Magnetohydrodynamics modeling==
In the context of numerical [[magnetohydrodynamics|MHD]] modeling, a fluxon is a discretized magnetic field line, representing a finite amount of magnetic flux in a localized bundle in the model.  Fluxon models are explicitly designed to preserve the [[topology]] of the magnetic field, overcoming [[numerical resistivity]] effects in [[Lagrangian and Eulerian coordinates|Eulerian models]].

==References==

{{Reflist}}

==External links==
* [http://flux.boulder.swri.edu FLUX], a fluxon-based MHD simulator

[[Category:Theoretical physics]]
[[Category:Superconductivity]]
[[Category:Josephson_effect]]