title: Three-dimensional photogrammetric measurement of magnetic field lines in the WEGA stellarator.
abstract: The magnetic confinement of plasmas in fusion experiments can significantly degrade due to perturbations of the magnetic field. A precise analysis of the magnetic field in a stellarator-type experiment utilizes electrons as test particles following the magnetic field line. The usual fluorescent detector for this electron beam limits the provided information to two-dimensional cut views at certain toroidal positions. However, the technique described in this article allows measuring the three-dimensional structure of the magnetic field by means of close-range photogrammetry. After testing and optimizing the main diagnostic components, measurements of the magnetic field lines were accomplished with a spatial resolution of 5 mm. The results agree with numeric calculations, qualifying this technique as an additional tool to investigate magnetic field configurations in a stellarator. For a possible future application, ways are indicated on how to reduce experimental error sources.
authors.affiliation: Max-Planck-Institut für Plasmaphysik, EURATOM Association, Wendelsteinstr. 1, D-17491 Greifswald, Germany. peter.drewelow@ipp.mpg.de
authors.forename: Peter
authors.initials: P
authors.lastname: Drewelow
authors.forename: Torsten
authors.initials: T
authors.lastname: Bräuer
authors.forename: Matthias
authors.initials: M
authors.lastname: Otte
authors.forename: Friedrich
authors.initials: F
authors.lastname: Wagner
authors.forename: Andreas
authors.initials: A
authors.lastname: Werner