TJ-II:Magnetic coordinates: Difference between revisions

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In order to make comparisons between diagnostics, it is useful to convert these real-space coordinates to [[flux coordinates]]. This coordinate transform depends on the particular magnetic configuration used in a given experiment. Two tools are available to do so ([http://www-fusion.ciemat.es/cgi-bin/dir/dirnew.cgi?manuals/geometry_TJII/ See the on-line documentation] - only internal laboratory access):

First, vacuum equilibrium calculations from [[VMEC]]. These are then used to obtain magnetic flux coordinates <math>(\psi, \theta, \phi)</math>. A set of routines is available to perform the corresponding coordinate transforms.<ref>[[File:TJ2 Library V2.pdf]]: TJ-II Library Manual, Technical report 963, CIEMAT, 2001</ref> ~~The drawback of the VMEC calculations is (a) that magnetic islands are ignored, and (b) that only a limited number of configurations is available.~~<ref>[https://info.fusion.ciemat.es/InternalReport/IR1532.pdf TJ-II Webservices], Technical report 1532, CIEMAT, 2024</ref>

First, vacuum equilibrium calculations from [[VMEC]]. These are then used to obtain magnetic flux coordinates <math>(\psi, \theta, \phi)</math>. A set of routines is available to perform the corresponding coordinate transforms.<ref>[[File:TJ2 Library V2.pdf]]: TJ-II Library Manual, Technical report 963, CIEMAT, 2001</ref><ref>[https://info.fusion.ciemat.es/InternalReport/IR1532.pdf TJ-II Webservices], Technical report 1532, CIEMAT, 2024</ref> The drawback of the VMEC calculations is (a) that magnetic islands are ignored, and (b) that only a limited number of configurations is available.

Second, magnetic field line calculations using the [[:Wikipedia:Biot_savart|Biot-Savart Law]]. The approximate magnetic flux is recovered from an interpolation procedure. A set of routines is available to perform the corresponding coordinate transforms. More information can be found in files [http://www-fusion.ciemat.es/cgi-bin/dir/dirnew.cgi?manuals/geometry_TJII/ g3d_readme.doc and g3d_gridfile.doc]. Since the latter procedure is more flexible and generally applicable than the VMEC-based calculations, the latter is preferred.

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 In order to make comparisons between diagnostics, it is useful to convert these real-space coordinates to [[flux coordinates]]. This coordinate transform depends on the particular magnetic configuration used in a given experiment. Two tools are available to do so ([http://www-fusion.ciemat.es/cgi-bin/dir/dirnew.cgi?manuals/geometry_TJII/ See the on-line documentation] - only internal laboratory access):
-First, vacuum equilibrium calculations from [[VMEC]]. These are then used to obtain magnetic flux coordinates <math>(\psi, \theta, \phi)</math>. A set of routines is available to perform the corresponding coordinate transforms.<ref>[[File:TJ2 Library V2.pdf]]: TJ-II Library Manual, Technical report 963, CIEMAT, 2001</ref> The drawback of the VMEC calculations is (a) that magnetic islands are ignored, and (b) that only a limited number of configurations is available.<ref>[https://info.fusion.ciemat.es/InternalReport/IR1532.pdf TJ-II Webservices], Technical report 1532, CIEMAT, 2024</ref>
+First, vacuum equilibrium calculations from [[VMEC]]. These are then used to obtain magnetic flux coordinates <math>(\psi, \theta, \phi)</math>. A set of routines is available to perform the corresponding coordinate transforms.<ref>[[File:TJ2 Library V2.pdf]]: TJ-II Library Manual, Technical report 963, CIEMAT, 2001</ref><ref>[https://info.fusion.ciemat.es/InternalReport/IR1532.pdf TJ-II Webservices], Technical report 1532, CIEMAT, 2024</ref> The drawback of the VMEC calculations is (a) that magnetic islands are ignored, and (b) that only a limited number of configurations is available.
 Second, magnetic field line calculations using the [[:Wikipedia:Biot_savart|Biot-Savart Law]]. The approximate magnetic flux is recovered from an interpolation procedure. A set of routines is available to perform the corresponding coordinate transforms. More information can be found in files [http://www-fusion.ciemat.es/cgi-bin/dir/dirnew.cgi?manuals/geometry_TJII/ g3d_readme.doc and g3d_gridfile.doc]. Since the latter procedure is more flexible and generally applicable than the VMEC-based calculations, the latter is preferred.