Separatrix: Difference between revisions

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In the fusion context, the term refers to the trajectories of the magnetic field lines and is used to describe:
In the fusion context, the term refers to the trajectories of the magnetic field lines and is used to describe:
* The boundary between closed and open field lines, separating the toroidally confined region from the region where field lines connect to material surfaces - in the case of a [[Divertor|divertor]] configuration in [[Tokamak|tokamaks]], or a similar situation in other devices.
* In the case of a [[Divertor|divertor]] configuration in [[Tokamak|tokamaks]], or a similar situation in other devices: the boundary between closed and open field lines, separating the toroidally confined region from the region where field lines connect to material surfaces.
* The boundary between the inside of a magnetic island and the surrounding region.
* The boundary between the inside of a magnetic island and the surrounding region.


In the case of plasmas that are limited by material objects (limiters or walls),
In the case of plasmas that are limited by material objects (limiters or walls),
it is not strictly correct to speak of a separatrix to describe the boundary between the confined plasma and
the use of the term separatrix to describe the boundary between the confined plasma and
the external part of the plasma that connects to the wall (the Scrape-Off Layer, SOL).  
the external part of the plasma that connects to the wall (the Scrape-Off Layer, SOL) is not correct.  
In this case, it is better to refer to this boundary as the Last Closed Magnetic Surface (LCMS) or Last Closed Flux Surface (LCFS).
In this case, the boundary should be referred to as the Last Closed Magnetic Surface (LCMS) or Last Closed Flux Surface (LCFS).


== See also ==
== See also ==

Revision as of 20:25, 15 February 2010

A separatrix is a boundary between domains with distinct dynamical behaviour (phase curves) in a dynamical system. [1] [2]

In the fusion context, the term refers to the trajectories of the magnetic field lines and is used to describe:

  • In the case of a divertor configuration in tokamaks, or a similar situation in other devices: the boundary between closed and open field lines, separating the toroidally confined region from the region where field lines connect to material surfaces.
  • The boundary between the inside of a magnetic island and the surrounding region.

In the case of plasmas that are limited by material objects (limiters or walls), the use of the term separatrix to describe the boundary between the confined plasma and the external part of the plasma that connects to the wall (the Scrape-Off Layer, SOL) is not correct. In this case, the boundary should be referred to as the Last Closed Magnetic Surface (LCMS) or Last Closed Flux Surface (LCFS).

See also

References