Effective plasma radius: Difference between revisions
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→Effective radius based on flux
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Here, ''R'' is the [[Toroidal coordinates|major radius]] of the [[:Wikipedia:Torus|torus]]. | Here, ''R'' is the [[Toroidal coordinates|major radius]] of the [[:Wikipedia:Torus|torus]]. | ||
Particularly in helical systems, choosing a value of ''R'' may be inappropriate (since the magnetic axis is not a circle, and the shape of the flux surfaces is not close to a toroid). | Particularly in helical systems, choosing a value of ''R'' may be inappropriate (since the magnetic axis is not a circle, and the shape of the flux surfaces is not close to a toroid). | ||
One can avoid making an (arbitrary) choice for ''R'' by defining | One can avoid making an (arbitrary) choice for ''R'' by defining | ||
* ''r''<sub>eff</sub> = 2''V/S'' (this still implicitly assumes the surfaces are | * ''r''<sub>eff</sub> = 2''V/S'' (this still implicitly assumes the surfaces are very similar to a torus) | ||
A different approach is offered by recognizing that the flux surfaces are topological toroids of a single parameter. | |||
Then, the surface area and volume corresponding to such surfaces are related. | |||
Assuming only that ''S'' is linear in ''r''<sub>eff</sub> (or ''V'' is cuadratic in ''r''<sub>eff</sub>), it follows that: | |||
* ''r''<sub>eff</sub> = ''dV/dS'' (more general) | |||
== Effective radius based on field lines == | == Effective radius based on field lines == | ||