Rotational transform: Difference between revisions

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Assuming the existence of toroidally nested magnetic [[Flux surface|flux surfaces]], the rotational transform (field line pitch) is defined as
The rotational transform (or field line pitch) ''ι/2π'' is defined as the mean number of toroidal transits (''n'') divided by the mean number of poloidal transits (''m'') of a field line on a toroidal flux surface.
Assuming the existence of toroidally nested magnetic [[Flux surface|flux surfaces]], it may be  defined as
<ref>[http://link.aps.org/doi/10.1103/RevModPhys.76.1071 A.H. Boozer, ''Physics of magnetically confined plasmas'', Rev. Mod. Phys. '''76''' (2004) 1071]</ref>
<ref>[http://link.aps.org/doi/10.1103/RevModPhys.76.1071 A.H. Boozer, ''Physics of magnetically confined plasmas'', Rev. Mod. Phys. '''76''' (2004) 1071]</ref>


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where ''&psi;'' is the poloidal magnetic flux, and ''&phi;'' the toroidal magnetic flux.
where ''&psi;'' is the poloidal magnetic flux, and ''&phi;'' the toroidal magnetic flux.
Thus, ''&iota;/2&pi;'' is the mean number of toroidal transits (''n'') divided by the
mean number of poloidal transits (''m'') of a field line on a flux surface.


== Safety factor ==
== Safety factor ==
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