1. Torsten Bräuer and the Metrologyteam
Max-Planck-Institut für Plasmaphysik, EURATOM Association, TI Greifswald
Metrology Methods and Results of Assembly of the first two Magnet Modules of Wendelstein 7-X
Torsten Bräuer and the Metrologyteam
Motivation
Wendelstein 7-X is an advanced super conducting fusion experiment to confirm that the stellarator principle can be used for power plants
A very high geometric precision is necessary during manufacture and assembly since:
A high precision of magnetic field ( ≈ 2·10-4) is essential for a good plasma confinement and an even distribution of the power load on the divertor targets
Avoid geometric collisions
A high geometric precision during assembly requires:
Appropriated survey strategies
Precise measurement tools
Key foundings
Two (out of 5) magnet system modules are assembled, 3-rd module is nearly completed
Required assembly tolerances have been achieved
For coil adjustment ≤ 1.5 mm
For module assembly ≤ 4.2 mm
Accessibility of first order ref.-points decreases drastically with ongoing assembly progress
Laser-Tracker as well as Photogrammetry can not always deliver an appropriate number of ref.-points; in such cases both techniques have to be used in combination
4 basic metrology techniques, Laser-Tracker, Photogrammetry, articulated arm and surface scanner can serve all survey tasks during assembly of Wendelstein 7-X
Schematic view of the Wendelstein 7-X experiment
Modul #1
Modul #5
Coil package of a half module (step 1)
Half module (after step 3) on the hook. It is moved to next assembly stand, were two half modules are joined
Deviation interval (Min-Max) of coil ref.-points measured by Laser-Tracker; Reference co-ordinates from manufacturer; Number of accessible points in general ≥5 but with exceptions, in such cases additional Photogrammetry points have to be used
Main Assembly steps
Adjustment of 7 coil
in machine table COSY each coil ref.-point has to be inside: r ≤ 1.5mm
(blue columns and tolerance boarder line)
Assembly of support structure
in best-fit COSY of coils each ref.-point has to be inside:
Assembly of inter coils connections (LSE)
welding of massive steel blocks between coils
(green columns)
Joining of to half modules
in best-fit COSY of support structure each coil ref.-point
has to be inside: r ≤ 4.2mm
(red columns and tolerance boarder line)
One module of the magnet system with coils, support structure, plasma vessel and bus bars
(step 4)
Module (after step 4) during movement to the next assembly stand;
By additional brackets (yellow) deformation of coil system is reduced to a minimum
Main Measurement systems for component adjustment
Laser-Tracker with T-Probe:
practical accuracy in assembly stand, including system orientation and using of adapters < 0.3 mm
Photogrammetry system AICON 3D Studio:
practical accuracy in a volume of  10 x 5 x 5 m of the assembly stand, including using of adapters: < 0.3 mm
Accessibility of ref.-points after module assembly (step 4)
9th ISFNT, Dalian, China, Oct. 2009