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Greenwald limit: Difference between revisions
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where ''n<sub>G</sub>'' is the density in 10<sup>10</sup> m<sup>-3</sup>, ''I<sub>p</sub>'' the plasma current in MA, and ''a'' the minor radius in m. | where ''n<sub>G</sub>'' is the density in 10<sup>10</sup> m<sup>-3</sup>, ''I<sub>p</sub>'' the plasma current in MA, and ''a'' the minor radius in m. | ||
In tokamaks (and RFPs), exceeding the Greenwald limit typically leads to a disruption, although sometimes the limit can be crossed without deleterious effects (especially with peaked density profiles). Stellarators can typically exceed the Greenwald limit by factors of 2 or more (replacing ''I<sub>p</sub>'' by the | In tokamaks (and RFPs), exceeding the Greenwald limit typically leads to a disruption, although sometimes the limit can be crossed without deleterious effects (especially with peaked density profiles). Stellarators can typically exceed the Greenwald limit by factors of 2 to 5, or more (replacing ''I<sub>p</sub>'' by an equivalent current corresponding to the magnetic field). | ||
The mechanism behind this phenomenological limit is not understood, but probably associated with edge gradient limits. | The mechanism behind this phenomenological limit is not understood, but probably associated with edge gradient limits. | ||